Add dummy state for client_certifiate

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index d1646eb..14884aa 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -1142,7 +1142,18 @@
                 mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO );
                 break;
             case MBEDTLS_SSL_CLIENT_CCS_AFTER_SERVER_FINISHED:
-                mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_FINISHED );
+#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
+                if( ssl->handshake->client_auth )
+                {
+                    mbedtls_ssl_handshake_set_state( ssl,
+                                            MBEDTLS_SSL_CLIENT_CERTIFICATE );
+                }
+                else
+#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
+                {
+                    mbedtls_ssl_handshake_set_state( ssl,
+                                            MBEDTLS_SSL_CLIENT_FINISHED );
+                }
                 break;
             default:
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );