drm/i915/color: Program Plane Post CSC Registers

drm/i915/color: Program Plane Post CSC Registers

Extract the LUT and program plane post csc registers.

v2: Add DSB support
v3: Add support for single segment 1D LUT
v4:
- s/drm_color_lut_32/drm_color_lut32 (Simon)
- Move declaration to beginning of the function (Suraj)
- Remove multisegmented code, add it later
- Remove dead code for SDR planes, add it later
v5:
- Fix iterator issues
v6: Removed redundant variable (Suraj)

Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Link: https://patch.msgid.link/20251203085211.3663374-13-uma.shankar@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>