sched: Add snapshot of sched_{up,down}migrate knobs

This snapshot is taken from msm-4.14 as of commit 40bd7878710ab4f
("sched: Don't fail isolation request for an already isolated CPU").

Change-Id: I9a52e67862ee5086880884128102aa4f8efb04ce
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>