sched: walt: Improve the scheduler

This change is for general scheduler improvements.

Change-Id: Ib8505248b91fb33395fe53f2dfacc8ec68c0273c
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>
[satyap@codeaurora.org: resolution of trivial merge conflicts]
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>