Peter Zijlstra suggested to simplify SCHED_FEAT_* checks via the
sched_feat(x) macro.

No code changed:

   text    data     bss     dec     hex filename
   38895    3550      24   42469    a5e5 sched.o.before
   38895    3550      24   42469    a5e5 sched.o.after
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>