sched: EAS/WALT: finish accounting prior to task_tick

In order to set rq->misfit_task in time, call update_task_ravg() prior
to task_tick.  This reduces upmigration delay by 1 scheduler window.

Change-Id: I7cc80badd423f2e7684125fbfd853b0a3610f0e8
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>