sched: Remove ASYM_GRAN feature
This features has been enabled for quite a while, after testing showed that
easing preemption for light tasks was harmful to high priority threads.
Remove the feature flag.
Signed-off-by: Mike Galbraith <firstname.lastname@example.org>
Signed-off-by: Peter Zijlstra <email@example.com>
Signed-off-by: Ingo Molnar <firstname.lastname@example.org>