x86, io_apic: Move irq_remapping_enabled checks out of check_timer()

Move these checks to IRQ remapping code by introducing the
panic_on_irq_remap() function.

Signed-off-by: Joerg Roedel <joro@8bytes.org>
Acked-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>