[PKT_SCHED]: Missing qdisc destroy in sch_netem.

The underlying qdisc was not being properly destroyed, shows up as
assertion failure on device removal.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@redhat.com>

net/sched/sch_netem.c

@@ -806,6 +806,9 @@ static void netem_destroy(struct Qdisc *sch)
 	struct netem_sched_data *q = (struct netem_sched_data *)sch->data;
 
 	del_timer_sync(&q->timer);
+
+	qdisc_destroy(q->qdisc);
+	q->qdisc = &noop_qdisc;
 }
 
 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)