net_sched: Add qdisc_enqueue wrapper

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 444c227..7d705b8 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -133,7 +133,8 @@
 		return NET_XMIT_DROP;
 	}
 
-	if ((ret = q->qdisc->enqueue(skb, q->qdisc)) != 0) {
+	ret = qdisc_enqueue(skb, q->qdisc);
+	if (ret != 0) {
 		sch->qstats.drops++;
 		return ret;
 	}