Revert "sched/core: Fix migration to invalid CPU in __set_cpus_allowed_ptr()"

This reverts commit 5d498864.

This is a preparation change for merging android-4.14-q.149 into
msm-4.14 branch.The reverted change is committed already as:

98164f45 sched/core: Fix warning introduced in __set_cpus_allowed_ptr

Change-Id: I9381e1518e3c4494b8abf6adedcf5c4459662bf3
Signed-off-by: Blagovest Kolenichev <bkolenichev@codeaurora.org>