drm/amd/display: Fix DMSS not triggering for HDR to SDR transition

drm/amd/display: Fix DMSS not triggering for HDR to SDR transition

Why:
DMSS feature was not getting triggered during HDR to SDR transitions,
and no DPCD write was observed. Root cause analysis revealed that
incorrect panel capabilities were being reported for PSR SU panels.
Due to the wrong capabilities, the OS was not invoking the DMSS API,
resulting in no DPCD communication and also gate eDP teardown across
DMSS hold

How:
Fixed by setting the correct power panel capabilities for PSR SU panels.
This ensures the OS receives accurate panel capability information and
triggers the DMSS API as expected, restoring proper DPCD writes during
HDR to SDR transitions.
The DC commit sequence,was tearing the eDP down anyway -- backlight off, ABM disable,
DPMS off, PSR/Replay feature_enabled cleared, PHY TX off, OTG/OPTC off
all these actions are blocked now with the skip_implict_edp_power_control

Reviewed-by: Aric Cyr <aric.cyr@amd.com>
Signed-off-by: Karthi Kandasamy <karthi.kandasamy@amd.com>
Signed-off-by: George Zhang <george.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>