sched: EAS: fix sync-wakeup task placement logic

At present, scheduler places wakee on waker blindly as long as waker
CPU isn't overutilized.  This can cause excessive task packing which
will lead both power and performance suboptimality.

Fix such suboptimality by subtracting waker CPU's current task load
prior to compare CPUs load.

Change-Id: I25c8962653138ec710688bf467d15c7055b7b3b7
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>