make dequeue_entity() / enqueue_entity() and update_stats_dequeue() /
update_stats_enqueue() look similar, structure-wise.

zero effect, functionality-wise:

   text    data     bss     dec     hex filename
  34550    3026     100   37676    932c sched.o.before
  34550    3026     100   37676    932c sched.o.after
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>