[NET_SCHED]: sch_cbq: use hrtimer for delay_timer

Switch delay_timer to hrtimer.

The class penalty parameter is changed to use psched ticks as units.
Since iproute never supported using this and the only existing user
(libnl) incorrectly assumes psched ticks as units anyway, this
shouldn't break anything.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>