detect failures, and get different PCI IDs.
For the former the interface returns an int to signal an error. The ID is
returned at a uintptr_t * argument.
For the latter there is a type argument that allows selecting the ID type.
This only specifies a single type, however a MSI type will be added
to handle the need to find the ID the hardware passes to the ARM GICv3
interrupt controller.
A follow up commit will be made to remove pci_get_rid.
Reviewed by: jhb, rstone
Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D6239