acpi_resource: support multiple IRQs

Some DSDT entries have multiple interrupts for one device.
Add support for it.

This fixes ahci on NXP LS2160 and genet on RPi4

Submitted by: Greg V <greg@unrelenting.technology>
Reviewed by: jhb
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D25145