drm/amd/display: Temporary Disable MST DP Colorspace Property

Create MST colorsapce property for downstream device would trigger
warning message "RIP: 0010:drm_mode_object_add+0x8e/0xa0 [drm]"

After driver is loaded and drm device is registered, create
dp colorspace property triggers warning storm at
WARN_ON(!dev->driver->load && dev->registered && !obj_free_cb);

Temporary disabling MST dp colorspace property for now.

Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>