sched: Clean up SCHED_RESET_ON_FORK

Make SCHED_RESET_ON_FORK sched_fork() bits a self-contained unlikely code path.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Lennart Poettering <mzxreary@0pointer.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1245228361.18329.6.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>