net-sched: change tcf_destroy_chain() to clear start of filter list

Pass double tcf_proto pointers to tcf_destroy_chain() to make it
clear the start of the filter list for more consistency.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mac80211/wme.c

@@ -323,8 +323,7 @@ static void wme_qdiscop_destroy(struct Qdisc* qd)
 	struct ieee80211_hw *hw = &local->hw;
 	int queue;
 
-	tcf_destroy_chain(q->filter_list);
-	q->filter_list = NULL;
+	tcf_destroy_chain(&q->filter_list);
 
 	for (queue=0; queue < hw->queues; queue++) {
 		skb_queue_purge(&q->requeued[queue]);