Enable multi session tickets on Server

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 0b3ba90..2621d20 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -624,6 +624,9 @@
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
     uint8_t tls13_kex_modes; /*!< Key exchange modes supported by the client */
 #endif
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+    int tls13_session_tickets;         /*!< number of session tickets */
+#endif
 #endif /* MBEDTLS_SSL_SRV_C */
 
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */