linuxkpi: pci: Add more functions needed by drm

Mostly stubs to satisfy building

Reviewed by: hselasky
Obtained from: drm-kmod
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D35938

(cherry picked from commit 6890e327a86da0c268f2b21637bce4891626ada0)