drm/amd/display: Set color_mgmt_changed to true on unsuspend

Otherwise we can end up with a frame on unsuspend where color management
is not applied when userspace has not committed themselves.

Fixes re-applying color management on Steam Deck/Gamescope on S3 resume.

Signed-off-by: Joshua Ashton <joshua@froggi.es>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>