sched/fair: Improve the scheduler

This change is for general scheduler improvement.

Change-Id: Ice00d43c70be105b5bc3ad09caa6047aa98d7402
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
[clingutla@codeaurora.org: Resolved trivial merge conflicts.]
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>