drm/i915/color: Add registers for 3D LUT

drm/i915/color: Add registers for 3D LUT

Add registers needed to program 3D LUT

v2:
- Follow convention documented in i915_reg.h (Jani)
- Removing space in trailer (Suraj)
- Move registers to intel_color_regs.h

BSpec: 69378, 69379, 69380
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patch.msgid.link/20251203085211.3663374-14-uma.shankar@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>