libmbedtls: Support DSA algorithm

DSA is not supported in MbedTLS, use libtomcrypt instead.

Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/include/mbedtls_config_kernel.h b/lib/libmbedtls/include/mbedtls_config_kernel.h
index d8ade1d..63f8d5d 100644
--- a/lib/libmbedtls/include/mbedtls_config_kernel.h
+++ b/lib/libmbedtls/include/mbedtls_config_kernel.h
@@ -63,8 +63,7 @@
 #define MBEDTLS_CIPHER_C
 #endif
 
-#if defined(CFG_CRYPTO_RSA) || defined(CFG_CRYPTO_DSA) || \
-    defined(CFG_CRYPTO_DH) || defined(CFG_CRYPTO_ECC)
+#if defined(CFG_CRYPTO_RSA) || defined(CFG_CRYPTO_DH) || defined(CFG_CRYPTO_ECC)
 #define MBEDTLS_BIGNUM_C
 #define MBEDTLS_OID_C
 #define MBEDTLS_PKCS1_V15