sched: Export sched_setscheduler_nocheck() for qhmp

Export sched_setscheduler_nocheck() so that external
kernel modules can use it for qhmp scheduler.

Change-Id: Ifd819cf9ec9ad29542dec7dc57a444e235962676
Signed-off-by: Hanumath Prasad <hpprasad@codeaurora.org>