pci_host_generic: Properly handle bus_release_resource of IRQ resources

Unlike other bus methods updated to use bus_generic_rman_* in commit
d79b6b8ec267, the bus_release_resource method was using
bus_generic_rman_release_resource for all types other than
PCI_RES_BUS. Instead, bus_generic_rman_* should only be used for
memory and I/O port resources for this driver.

Tested by: cperciva
Reviewed by: cperciva
Fixes: d79b6b8ec267 pci_host_generic: Don't rewrite resource start address for translation
Differential Revision: https://reviews.freebsd.org/D43925