vhost: fix incorrect print type

fix incorrect print type in vhost_virtqueue_stop

Signed-off-by: Jie Wang <wangjie88@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <1556605773-42019-1-git-send-email-wangjie88@huawei.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/virtio/vhost.c

@@ -1081,7 +1081,7 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
 
     r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
     if (r < 0) {
-        VHOST_OPS_DEBUG("vhost VQ %d ring restore failed: %d", idx, r);
+        VHOST_OPS_DEBUG("vhost VQ %u ring restore failed: %d", idx, r);
         /* Connection to the backend is broken, so let's sync internal
          * last avail idx to the device used idx.
          */