drm/amd/display: DML2.1 Reintegration for Various Fixes

[Why and How]
DML2.1 reintegration for several fixes and updates to the DML
code.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Austin Zheng <Austin.Zheng@amd.com>
Signed-off-by: Roman Li <roman.li@amd>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>