sched: Optimize task_rq_lock()

sched: Optimize task_rq_lock()

commit 65cc8e4859ff29a9ddc989c88557d6059834c2a2 upstream.

Now that we hold the rq->lock over set_task_cpu() again, we can do
away with most of the TASK_WAKING checks and reduce them again to
set_cpus_allowed_ptr().

Removes some conditionals from scheduling hot-paths.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Oleg Nesterov <oleg@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>