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/sch_sfq.c b/net/sched/sch_sfq.c
index 6a97afb..8458f63 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -461,7 +461,7 @@
 		return -EINVAL;
 
 	sch_tree_lock(sch);
-	q->quantum = ctl->quantum ? : psched_mtu(sch->dev);
+	q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch));
 	q->perturb_period = ctl->perturb_period * HZ;
 	if (ctl->limit)
 		q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1);
@@ -502,7 +502,7 @@
 	q->max_depth = 0;
 	q->tail = SFQ_DEPTH;
 	if (opt == NULL) {
-		q->quantum = psched_mtu(sch->dev);
+		q->quantum = psched_mtu(qdisc_dev(sch));
 		q->perturb_period = 0;
 		q->perturbation = net_random();
 	} else {