drm/i915/dp: Fix VSC dynamic range signaling for RGB formats

drm/i915/dp: Fix VSC dynamic range signaling for RGB formats

For RGB, set dynamic_range to CTA or VESA based on
crtc_state->limited_color_range so sinks apply correct
quantization. YCbCr remains limited (CTA) range.
(DP v1.4, Table 5-1)

v2:
- Added Reported-by and Tested-by tags

v3:
- Add back YCbCr comment(Suraj)

Cc: stable@vger.kernel.org #v5.8+
Reported-by: DeepChirp <DeepChirp@outlook.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/15874
Tested-by: DeepChirp <DeepChirp@outlook.com>
Fixes: 9799c4c3b76e ("drm/i915/dp: Add compute routine for DP VSC SDP")
Assisted-by: GitHub-Copilot:GPT-5.4
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260505090920.2479112-1-chaitanya.kumar.borah@intel.com
(cherry picked from commit 38e10ddae6f8d42a2e8437fcd25a1cac51106c64)
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>