[NET]: Make and use skb_get_queue_mapping

Make the helper for getting the field, symmetrical to
the "set" one. Return 0 if CONFIG_NETDEVICES_MULTIQUEUE=n

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index be57cf3..a9fad71 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -266,7 +266,7 @@
 	int busy;
 	int nores;
 	int len = skb->len;
-	int subq = skb->queue_mapping;
+	int subq = skb_get_queue_mapping(skb);
 	struct sk_buff *skb_res = NULL;
 
 	start = master->slaves;