MINOR: sched: do not requeue a tasklet into the current queue

MINOR: sched: do not requeue a tasklet into the current queue

As found by Christopher, the concept of waking a tasklet up into the
current queue is totally flawed, because if a task is in TL_BULK or
TL_HEAVY, all the tasklets it will wake up will end up in the same
queue. Not only this will clobber such queues, but it will also
reduce their quality of service, and this can contaminate other
tasklets due to the numerous wakeups there are now with the subsribe
mechanism between layers.