sched: Make hrtick_notifier an explicit call

No need for an extra notifier. We don't need to handle all these states. It's
sufficient to kill the timer when the cpu dies.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160310120025.770528462@linutronix.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>