drm/i915: Add the VBT LTTPR transparent vs. non-transparent bits

VBT gained a bit to indicate whether LTTPRs should use transparent
or non-transparent mode. Dunno if we should actually look at this...

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220715202044.11153-6-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>