virtio-net: do not reset vlan filtering at set_features

This function is called after virtio_load, so all vlan configuration is
lost in migration case.

Just allow all the vlan-tagged packets if vlan is not configured, and
trust device reset to clear all filtered vlans.

Fixes: 0b1eaa8 ("virtio-net: Do not filter VLANs without F_CTRL_VLAN")
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Hawkins Jiawei <yin31149@gmail.com>
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Message-Id: <95af0d013281282f48ad3f47f6ad1ac4ca9e52eb.1690106284.git.yin31149@gmail.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/net/virtio-net.c

@@ -1029,9 +1029,7 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
         vhost_net_save_acked_features(nc->peer);
     }
 
-    if (virtio_has_feature(features, VIRTIO_NET_F_CTRL_VLAN)) {
-        memset(n->vlans, 0, MAX_VLAN >> 3);
-    } else {
+    if (!virtio_has_feature(features, VIRTIO_NET_F_CTRL_VLAN)) {
         memset(n->vlans, 0xff, MAX_VLAN >> 3);
     }