drm/i915/display: drop redundant display/ from #includes

Drop the redundant sub-directory from #includes under display/. Group
and sort the results.

v2: Rebase

Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230104153258.453431-1-jani.nikula@intel.com