net: Fix more stale on-stack list_head objects.

From: Eric W. Biederman <ebiederm@xmission.com>

In the beginning with batching unreg_list was a list that was used only
once in the lifetime of a network device (I think).  Now we have calls
using the unreg_list that can happen multiple times in the life of a
network device like dev_deactivate and dev_close that are also using the
unreg_list.  In addition in unregister_netdevice_queue we also do a
list_move because for devices like veth pairs it is possible that
unregister_netdevice_queue will be called multiple times.

So I think the change below to fix dev_deactivate which Eric D. missed
will fix this problem.  Now to go test that.
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mac80211/iface.c

@@ -1229,6 +1229,7 @@ void ieee80211_remove_interfaces(struct ieee80211_local *local)
 	}
 	mutex_unlock(&local->iflist_mtx);
 	unregister_netdevice_many(&unreg_list);
+	list_del(&unreg_list);
 }
 
 static u32 ieee80211_idle_off(struct ieee80211_local *local,

net/sched/sch_generic.c

@@ -839,6 +839,7 @@ void dev_deactivate(struct net_device *dev)
 
 	list_add(&dev->unreg_list, &single);
 	dev_deactivate_many(&single);
+	list_del(&single);
 }
 
 static void dev_init_scheduler_queue(struct net_device *dev,