pkt_sched: Revert tasklet_hrtimer changes.

These are full of unresolved problems, mainly that conversions don't
work 1-1 from hrtimers to tasklet_hrtimers because unlike hrtimers
tasklets can't be killed from softirq context.

And when a qdisc gets reset, that's exactly what we need to do here.

We'll work this out in the net-next-2.6 tree and if warranted we'll
backport that work to -stable.

This reverts the following 3 changesets:

a2cb6a4d
("pkt_sched: Fix bogon in tasklet_hrtimer changes.")

38acce2d
("pkt_sched: Convert CBQ to tasklet_hrtimer.")

ee5f9757
("pkt_sched: Convert qdisc_watchdog to tasklet_hrtimer")

Signed-off-by: David S. Miller <davem@davemloft.net>