drm/amd/display: revert support for DID2.0 dsc passthrough

3x4K60 displays over MST with DSC enabled was not able to light up
due to this patch.

Signed-off-by: Jun Lei <jun.lei@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>