[VLAN] Use unregister_netdevice to prevent rtnl double-lock.

- vlan_device_event is called by the networking with rtnl_lock
held already, so if we use unregister_netdev we hang trying
to get the rtnl semaphore again.

net/8021q/vlan.c

@@ -626,7 +626,7 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
 			ret = unregister_vlan_dev(dev,
 						  VLAN_DEV_INFO(vlandev)->vlan_id);
 
-			unregister_netdev(vlandev);
+			unregister_netdevice(vlandev);
 
 			/* Group was destroyed? */
 			if (ret == 1)