[BRIDGE]: fix locking and memory leak in br_add_bridge

There are several bugs in error handling in br_add_bridge:
- when dev_alloc_name fails, allocated net_device is not freed
- unregister_netdev is called when rtnl lock is held
- free_netdev is called before netdev_run_todo has a chance to be run after
unregistering net_device

Signed-off-by: Jiri Benc <[e-mail]>
Signed-off-by: Stephen Hemminger <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/bridge/br_if.c

···
 	rtnl_lock();
 	if (strchr(dev->name, '%')) {
 		ret = dev_alloc_name(dev, dev->name);
-		if (ret < 0)
-			goto err1;
+		if (ret < 0) {
+			free_netdev(dev);
+			goto out;
+		}
 	}
 
 	ret = register_netdevice(dev);
 	if (ret)
-		goto err2;
+		goto out;
 
 	ret = br_sysfs_addbr(dev);
 	if (ret)
-		goto err3;
-	rtnl_unlock();
-	return 0;
-
- err3:
-	unregister_netdev(dev);
- err2:
-	free_netdev(dev);
- err1:
+		unregister_netdevice(dev);
+ out:
 	rtnl_unlock();
 	return ret;
 }