drm/amd/display: Fix writeback on DCN 3.2+

drm/amd/display: Fix writeback on DCN 3.2+

[ Upstream commit 9ef84a307582a92ef055ef0bd3db10fd8ac75960 ]

[WHAT]
1. Set no scaling for writeback as they are hardcoded in DCN3.2+.
2. Set no fast plane update for writeback commits.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>