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>
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 09969c1..2a3c97f 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1704,7 +1704,7 @@
 
 	BUG_TRAP(!cl->filters);
 
-	tcf_destroy_chain(cl->filter_list);
+	tcf_destroy_chain(&cl->filter_list);
 	qdisc_destroy(cl->q);
 	qdisc_put_rtab(cl->R_tab);
 	gen_kill_estimator(&cl->bstats, &cl->rate_est);
@@ -1728,10 +1728,8 @@
 	 * be bound to classes which have been destroyed already. --TGR '04
 	 */
 	for (h = 0; h < 16; h++) {
-		for (cl = q->classes[h]; cl; cl = cl->next) {
-			tcf_destroy_chain(cl->filter_list);
-			cl->filter_list = NULL;
-		}
+		for (cl = q->classes[h]; cl; cl = cl->next)
+			tcf_destroy_chain(&cl->filter_list);
 	}
 	for (h = 0; h < 16; h++) {
 		struct cbq_class *next;