wwan: core: multiple netdevs deletion support

Use unregister_netdevice_queue() instead of simple
unregister_netdevice() if the WWAN netdev ops does not provide a dellink
callback. This will help to accelerate deletion of multiple netdevs.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/wwan_core.c

@@ -882,7 +882,7 @@ static void wwan_rtnl_dellink(struct net_device *dev, struct list_head *head)
 	if (wwandev->ops->dellink)
 		wwandev->ops->dellink(wwandev->ops_ctxt, dev, head);
 	else
-		unregister_netdevice(dev);
+		unregister_netdevice_queue(dev, head);
 
 out:
 	/* release the reference */