sched: EAS: introduce cstate aware task placement

Placing newly waking up task onto a shallower C-state CPU gives good
advantage in power and performance wise.  Introduce initial version of
C-state aware task placement logic which makes task placement logic to
place newly waking up tasks onto the shallowest C-state CPU as long as
it doesn't increase OPP.

Change-Id: I06aa76d0a98695e5594f2709dc9a4054b0371676
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>