drm/i915: Drop the pointless linear legacy LUT load on CHV

We now bypass the legacy LUT when it's not needed, so
no point in filling it up with a linear LUT.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190327155045.28446-10-ville.syrjala@linux.intel.com