- Teach about support for PCI domains in FreeBSD >= 700053.
- Stop including pcivar.h from the kernel source on FreeBSD => 430000,
if this was ever necessary it no longer is since the introduction
of pciio.h.
- Catch up with FreeBSD returning ENODEV for non-existing devices.
- Fix on big-endian archs.
PR: 116827
Approved by: maintainer, netchild