drm/i915: Fix VLV color state readout

VLV was missed when the color.get_config() hook was added.
Remedy that.

Not really sure what the final plan here was since a bunch of
color related readout was left in intel_display.c anyway,
but that's for anothr day to figure out...

Cc: Jani Nikula <jani.nikula@intel.com>
Fixes: 9af09df ("drm/i915/color: move pre-SKL gamma and CSC enable read to intel_color")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231009145828.12960-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

Author: vsyrjala

drivers/gpu/drm/i915/display/intel_color.c

@@ -3702,6 +3702,7 @@ static const struct intel_color_funcs vlv_color_funcs = {
 	.read_luts = i965_read_luts,
 	.lut_equal = i965_lut_equal,
 	.read_csc = vlv_read_csc,
+	.get_config = i9xx_get_config,
 };
 
 static const struct intel_color_funcs i965_color_funcs = {