linuxkpi: Add linuxkpi_video module

This contain the hdmi code and the aperture code like in linux.

Differential Revision: https://reviews.freebsd.org/D44925
Reviewed by: bz
Obtained from: drm-kmod
Sponsored by: Beckhoff Automation GmbH & Co. KG

(cherry picked from commit 11d79c4756b7c85faf7c4a268c301a41ce0887b9)