sched: Optimize wakeup placement logic when need_idle is set

Try and find the min cstate CPU within the little cluster when a
task fits there. If there is no idle CPU return the least busy
CPU. Also Add a prev CPU bias when C-states or load is the same.

CRs-fixed: 1006303
Change-Id: I577cc70a59f2b0c5309c87b54e106211f96e04a0
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>