[Intel-gfx] Fixes that failed to backport to v4.13-rc1

[Jani Nikula]

Another kernel, another list of failed backports.

The following commits have been marked as Cc: stable or fixing something
in v4.13-rc1 or earlier, but failed to cherry-pick to
drm-intel-fixes. Please see if they are worth backporting, and please do
so if they are.

BR,
Jani.

54d20ed1fff2 ("drm/i915: Fix bad comparison in skl_compute_plane_wm, v2.")

-- 
Jani Nikula, Intel Open Source Technology Center