Change base on review

Fix comments
Add test cases for client authentication with empty certificate

Change-Id: Id8a741ddd997ca92e36832f26088eb0e67830ad8
Signed-off-by: XiaokangQian <xiaokang.qian@arm.com>
diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index 49ed112..17efa8c 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -594,8 +594,8 @@
             else
             {
                 MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_NO_CERT,
-                                              MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
-                return( MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
+                                              MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE  );
+                return( MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE );
             }
         }
 #endif /* MBEDTLS_SSL_SRV_C */
@@ -741,9 +741,9 @@
 
     mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CERTIFICATE,
                                         buf, buf_len );
-#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED */
 
 cleanup:
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED */
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate" ) );
     return( ret );