drm/i915/display: use GOSUB to program double buffered LUT registers

drm/i915/display: use GOSUB to program double buffered LUT registers

With addition of double buffered GAMMA registers in PTL, we can now
program them in the active region. Use GOSUB instruction of DSB to
program them.

It is done in the following steps:
	1. intel_color_prepare_commit()
		- If the platform supports, prepare a dsb instance (dsb_color)
		  hooked to DSB0.
		- Add all the register write instructions to dsb_color through
		  the load_lut() hook
                - Do not add the vrr_send_push() logic to the buffer as it
		  should be taken care by dsb_commit instance of DSB0
                - Finish preparation of the buffer by aligning it to 64 bit

	2. intel_atomic_dsb_finish()
		- Add the gosub instruction into the dsb_commit instance of DSB0
		  using intel_dsb_gosub()
		- If needed, add the vrr_send_push() logic to dsb_commit after it

v2: Refactor code to simplify commit completion flow.
    Add some helpers along the way (Ville)
v3: s/doubled/double and add display to commit message prefix (Uma)

Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250523062041.166468-9-chaitanya.kumar.borah@intel.com