ACPI/processor: Convert to hotplug state machine

Install the callbacks via the state machine.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-acpi@vger.kernel.org
Cc: rt@linutronix.de
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/20160906170457.32393-12-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>