sched/preempt: Remove PREEMPT_ACTIVE unmasking off in_atomic()

Now that PREEMPT_ACTIVE implies PREEMPT_DISABLE_OFFSET, ignoring
PREEMPT_ACTIVE from in_atomic() check isn't useful anymore.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431441711-29753-7-git-send-email-fweisbec@gmail.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>