x86/apic/uv: Convert to hotplug state machine

Install the callbacks via the state machine.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-19-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>