drm/i915: Drop unused lut tables from intel_plane

Those LUT where defined in the original sprite patch introducing intel_plane,
but were never used.

  commit b840d907
  Author: Jesse Barnes <jbarnes@virtuousgeek.org>
  Date:   Tue Dec 13 13:19:38 2011 -0800

    drm/i915: add SNB and IVB video sprite support v6

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
[danvet: Pimp commit message as suggested by Damien]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>