Add a PCI parser that's independent of the other stuff.

Add a PCI parser that's independent of the other stuff.

This doesn't actually remove the old one, but a later patch will when
it's replacing all that stuff.

This won't actually *work* yet, either, because the infrastructure to
use it (replacing "struct disk_info") won't land for a few more patches.

Signed-off-by: Peter Jones <pjones@redhat.com>