sched/fair: Improve the scheduler

This change is for general scheduler improvement.

Change-Id: I0caae436c933656c9a7b5135c6d4a8179be06631
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
[satyap@codeaurora.org: fix trivial merge conflicts]
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>