x86, msi: Use IRQ remapping specific setup_msi_irqs routine

Use seperate routines to setup MSI IRQs for both
irq_remapping_enabled cases.

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>