drm/amd/display: Initialize data structure for DalMpVisualConfirm.

[Why] Prevent unexpected color shows if DalMpVisualConfirm enable.
[How] Zero out color configuration data for DalMpVisualConfirm when initiating.

Signed-off-by: Hugo Hu <hugo.hu@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>