drm/i915: add quirk to invert brightness on Packard Bell NCL20

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44156


Reported-by: Alan Zimmerman <alan.zimm@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>