drm/amd/display: Add DCN2.1 changes to DML

Hook up the DML changes for renoir.

Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>