sched: Restore previous implementation of check_for_migration()

commit 3bda2b55 ("Merge android-4.4.96 (aed4c54a) into msm-4.4")
replaced HMP scheduler check_for_migration() implementation with
EAS scheduler implementation. This breaks HMP scheduler upmgiration
functionality. Fix this by restoring the previous implementation.

Change-Id: I3221f3efe42e1e43f8009cfa52c11afbb9d9c5b3
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>