remove MBEDTLS_ERR_SSL_TICKET_INVALID_KEX_MODE error

Return MBEDTLS_ERR_ERROR_GENERIC_ERROR when ticket_flags
are not compatible with advertised key exchange mode.

Signed-off-by: Pengyu Lv <pengyu.lv@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 654a7da..16317c0 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -169,7 +169,7 @@
      *
      * We regard the ticket with incompatible key exchange modes as not match.
      */
-    ret = MBEDTLS_ERR_SSL_TICKET_INVALID_KEX_MODE;
+    ret = MBEDTLS_ERR_ERROR_GENERIC_ERROR;
     MBEDTLS_SSL_DEBUG_TICKET_FLAGS(4,
                                    session->ticket_flags);
     if (mbedtls_ssl_tls13_check_kex_modes(ssl,