[Intel-gfx] [PATCH 0/5] drm/i915: Fix backlight regression caused by misconfigured VBT

[Scot Doyle]

commit c675949ec58ca50d5a3ae3c757892f1560f6e896
     drm/i915: do not setup backlight if not available according to VBT

caused a regression on machines with a misconfigured VBT. Add a quirk to 
assert the presence of a controllable backlight, overriding the VBT. Then 
apply this quirk to four Haswell-based Chromebook laptops.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=79813