Add PSA crypto module

New module psa_crypto.c (MBEDTLS_PSA_CRYPTO_C):
Platform Security Architecture compatibility layer on top of
libmedcrypto.

Implement psa_crypto_init function which sets up a RNG.

Add a mbedtls_psa_crypto_free function which deinitializes the
library.

Define a first batch of error codes.
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 052aed0..dc112a9 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2013,7 +2013,7 @@
  * Requires: MBEDTLS_AES_C or MBEDTLS_DES_C
  *
  */
-//#define MBEDTLS_CMAC_C
+#define MBEDTLS_CMAC_C
 
 /**
  * \def MBEDTLS_CTR_DRBG_C
@@ -2556,6 +2556,18 @@
 #define MBEDTLS_POLY1305_C
 
 /**
+* \def MBEDTLS_PSA_CRYPTO_C
+ *
+ * Enable the Platform Security Architecture cryptography API.
+ *
+ * Module:  library/psa_crypto.c
+ *
+ * Requires: MBEDTLS_CTR_DRBG_C, MBEDTLS_ENTROPY_C
+ *
+ */
+#define MBEDTLS_PSA_CRYPTO_C
+
+/**
  * \def MBEDTLS_RIPEMD160_C
  *
  * Enable the RIPEMD-160 hash algorithm.