LinuxKPI: pci: add [linuxkpi_]pci_get_device()

Add a version of pci_get_device() as linuxkpi_pci_get_device()
not (yet) supporting the last argument.
Due to conflicts we cannot redefine it as we would normally do
in LinuxKPI so drivers have to be adjusted.

Differential Revision: https://reviews.freebsd.org/D37593

(cherry picked from commit 8f61992d7cc1108cebc1337451a15a0af420984c)