Move irq_routing_table from x86 to generic.

There is nothing really x86-specific there, other platforms use
ACPI interrupt routing for PCI too.

Change-Id: Ib02e2917902a161c3d79a1049bcd16ba40bb7814
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5277
Reviewed-by: David Karoly <karolyd577@gmail.com>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>