Add some negative testing for ecdsa_verify()
diff --git a/include/mbedtls/ecdsa.h b/include/mbedtls/ecdsa.h
index a277715..259948d 100644
--- a/include/mbedtls/ecdsa.h
+++ b/include/mbedtls/ecdsa.h
@@ -120,7 +120,7 @@
* prescribed by SEC1 4.1.4 step 3.
*
* \return 0 if successful,
- * MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid
+ * MBEDTLS_ERR_ECP_VERIFY_FAILED if signature is invalid
* or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
*/
int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,