x86, io_apic: Remove irq_remapping_enabled check in setup_timer_IRQ0_pin

This function is only called when irq-remapping is disabled.

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>