sched: fair: Add load-balancing changes snapshot

This snapshot is taken from msm-4.9 as of commit 935c3e96d14c14d
(Revert "sched/fair: Limit sync wakeup bias to waker cpu").

Change-Id: I678c66d6fa4ac96c74892328d181aa334a5e2fa7
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
[satyap@codeaurora.org:
    1. Resolve merge conflicts
    2. Fix indentation issues
    3. Fix compilation issues for ARCH=um]
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>