x86/x2apic: Use state information for disable

Use the state information to simplify the disable logic further.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20150115211703.209387598@linutronix.de


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