Remove not used state

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index c73b8bb..1282cfc 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1594,10 +1594,6 @@
             ret = ssl_tls13_process_client_finished( ssl );
             break;
 
-        case MBEDTLS_SSL_FLUSH_BUFFERS:
-            ret = ssl_tls13_flush_buffers( ssl );
-            break;
-
         case MBEDTLS_SSL_HANDSHAKE_WRAPUP:
             ret = ssl_tls13_handshake_wrapup( ssl );
             break;