Add micro-ecc based ecc-files to mbedtls

The files are from https://github.com/intel/tinycrypt
Using commit 6e0eb53fc8403988f97345e94081b0453f47231d as a base.
diff --git a/include/tinycrypt/ecc_dsa.h b/include/tinycrypt/ecc_dsa.h
new file mode 100644
index 0000000..aca00bc
--- /dev/null
+++ b/include/tinycrypt/ecc_dsa.h
@@ -0,0 +1,139 @@
+/* ecc_dh.h - TinyCrypt interface to EC-DSA implementation */
+
+/*
+ * Copyright (c) 2014, Kenneth MacKay
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *
+ *    - Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *
+ *    - Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ *    - Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * @file
+ * @brief -- Interface to EC-DSA implementation.
+ *
+ *  Overview: This software is an implementation of EC-DSA. This implementation
+ *            uses curve NIST p-256.
+ *
+ *  Security: The curve NIST p-256 provides approximately 128 bits of security.
+ *
+ *  Usage:  - To sign: Compute a hash of the data you wish to sign (SHA-2 is
+ *          recommended) and pass it in to ecdsa_sign function along with your
+ *          private key and a random number. You must use a new non-predictable
+ *          random number to generate each new signature.
+ *          - To verify a signature: Compute the hash of the signed data using
+ *          the same hash as the signer and pass it to this function along with
+ *          the signer's public key and the signature values (r and s).
+ */
+
+#ifndef __TC_ECC_DSA_H__
+#define __TC_ECC_DSA_H__
+
+#include <tinycrypt/ecc.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Generate an ECDSA signature for a given hash value.
+ * @return returns TC_CRYPTO_SUCCESS (1) if the signature generated successfully
+ *         returns TC_CRYPTO_FAIL (0) if an error occurred.
+ *
+ * @param p_private_key IN -- Your private key.
+ * @param p_message_hash IN -- The hash of the message to sign.
+ * @param p_hash_size IN -- The size of p_message_hash in bytes.
+ * @param p_signature OUT -- Will be filled in with the signature value. Must be
+ * at least 2 * curve size long (for secp256r1, signature must be 64 bytes long).
+ *
+ * @warning A cryptographically-secure PRNG function must be set (using
+ * uECC_set_rng()) before calling uECC_sign().
+ * @note Usage: Compute a hash of the data you wish to sign (SHA-2 is
+ * recommended) and pass it in to this function along with your private key.
+ * @note side-channel countermeasure: algorithm strengthened against timing
+ * attack.
+ */
+int uECC_sign(const uint8_t *p_private_key, const uint8_t *p_message_hash,
+	      unsigned p_hash_size, uint8_t *p_signature, uECC_Curve curve);
+
+#ifdef ENABLE_TESTS
+/*
+ * THIS FUNCTION SHOULD BE CALLED FOR TEST PURPOSES ONLY.
+ * Refer to uECC_sign() function for real applications.
+ */
+int uECC_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
+		     unsigned int hash_size, uECC_word_t *k, uint8_t *signature,
+		     uECC_Curve curve);
+#endif
+
+/**
+ * @brief Verify an ECDSA signature.
+ * @return returns TC_SUCCESS (1) if the signature is valid
+ * 	   returns TC_FAIL (0) if the signature is invalid.
+ *
+ * @param p_public_key IN -- The signer's public key.
+ * @param p_message_hash IN -- The hash of the signed data.
+ * @param p_hash_size IN -- The size of p_message_hash in bytes.
+ * @param p_signature IN -- The signature values.
+ *
+ * @note Usage: Compute the hash of the signed data using the same hash as the
+ * signer and pass it to this function along with the signer's public key and
+ * the signature values (hash_size and signature).
+ */
+int uECC_verify(const uint8_t *p_public_key, const uint8_t *p_message_hash,
+		unsigned int p_hash_size, const uint8_t *p_signature, uECC_Curve curve);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __TC_ECC_DSA_H__ */