Fix missing TCP_PORT for printf in TCP server example (#270)

Also replace `%d` with `%u`

Co-authored-by: Viacheslav Lotsmanov <lotsmanov89@gmail.com>

pico_w/tcp_server/picow_tcp_server.c

@@ -197,7 +197,7 @@ static bool tcp_server_open(void *arg) {
 
     err_t err = tcp_bind(pcb, NULL, TCP_PORT);
     if (err) {
-        DEBUG_printf("failed to bind to port %d\n");
+        DEBUG_printf("failed to bind to port %u\n", TCP_PORT);
         return false;
     }