x86: Let x2APIC support depend on interrupt remapping or guest support

We are able to use x2APIC mode in the absence of interrupt remapping on
certain hypervisors. So it is fine to disable IRQ_REMAP without having
to give up x2APIC support.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Link: http://lkml.kernel.org/r/55479709.4030901@siemens.com


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