sched: EAS/WALT: Don't take into account of running task's util

For upmigrating misfit running task case, the currently running
task's util has been counted into cpu_util(). Thus currently
__cpu_overutilized() which add task's uitl twice is overestimated.

Change-Id: I5326f4c736a55679009d2e7293f8792311c04294
Signed-off-by: Ke Wang <ke.wang@spreadtrum.com>