act_mirred: Fix mirred_init_module error handling

If tcf_register_action failed, mirred_device_notifier
should be unregistered.

Fixes: 3b87956e ("net sched: fix race in mirred device removal")
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>

net/sched/act_mirred.c

@@ -484,7 +484,11 @@ static int __init mirred_init_module(void)
 		return err;
 
 	pr_info("Mirror/redirect action on\n");
-	return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
+	err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
+	if (err)
+		unregister_netdevice_notifier(&mirred_device_notifier);
+
+	return err;
 }
 
 static void __exit mirred_cleanup_module(void)