Revert "drm/i915: Parsing LFP brightness control from VBT"

This reverts commit 371abae8

.

This data seems unreliable and causing many issues and blocking other
teams and feature implementation. Safest way is to revert that for now.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88081
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88039
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87671
Cc: Vandana Kannan <vandana.kannan@intel.com>
Cc: Deepak M <m.deepak@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Kristian Høgsberg <hoegsberg@gmail.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>