sched/walt: improve the scheduler

This change is for general scheduler improvement.

Change-Id: Ie162a57537bb9ada66a4254d606e17d54b7a3a49
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
[pkondeti@codeaurora.org: code refactoring and implemented freq to load
calculations.]
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>