Rename ecdsa_signature_to_asn1 to mbedtls_ecdsa_signature_to_asn1

diff --git a/include/mbedtls/ecdsa.h b/include/mbedtls/ecdsa.h
index 7490c65..5b90de1 100644
--- a/include/mbedtls/ecdsa.h
+++ b/include/mbedtls/ecdsa.h
@@ -255,7 +255,7 @@
  *                  or a MBEDTLS_ERR_MPI_XXX or MBEDTLS_ERR_ASN1_XXX error code
  *
  */
-int ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s,
+int mbedtls_ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s,
                              unsigned char *sig, size_t *slen,
                              size_t ssize );