Revert "sched/fair: Rename check_preempt_wakeup() to check_preempt_wakeup_fair()"

This reverts commit 5787443f which is
commit 82845683 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I9b110a5e5d327c1592c2d4f37db125c3bce61ae5
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>