git: drm - Update to Linux 4.20.17

[Sergey Zigachev]

> FYI, I had to remove i915_load=YES from rc.conf in order to make it 
> work! I use Xorg from ravenports.
> 
> With the old kernel I had to use modesetting.

What issues do you have with i915_load? Did you test hardware acceleration?

Also, you might want to patch xorg-server and/or xf86-video-intel.

xorg-server: https://github.com/DragonFlyBSD/DeltaPorts/pull/1503
With this patch you can test modesetting driver with glamor hardware 
acceleration.

xf86-video-intel: https://github.com/DragonFlyBSD/DeltaPorts/pull/1502
This patch should improve performance with SNA hardware acceleration.

-Sergey