drm/amd/display: LSDMA support

[Why]
Driver should be able to send LSDMA commands to DMCUB

[How]
Driver can now send LSDMA commands to DMCUB.
DMCUB should process them and send to LSDMA controller.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Ostrowski Rafal <rostrows@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>