pkt_sched: Remove 'dev' member of struct Qdisc.

It can be obtained via the netdev_queue.  So create a helper routine,
qdisc_dev(), to make the transformations nicer looking.

Now, qdisc_alloc() now no longer needs a net_device pointer argument.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 9360fc8..e2389f1 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -334,7 +334,7 @@
 	tcm->tcm_family = AF_UNSPEC;
 	tcm->tcm__pad1 = 0;
 	tcm->tcm__pad1 = 0;
-	tcm->tcm_ifindex = tp->q->dev->ifindex;
+	tcm->tcm_ifindex = qdisc_dev(tp->q)->ifindex;
 	tcm->tcm_parent = tp->classid;
 	tcm->tcm_info = TC_H_MAKE(tp->prio, tp->protocol);
 	NLA_PUT_STRING(skb, TCA_KIND, tp->ops->kind);