drm/amd/display: Rework DCE transform bit depth reduction programming.

Clear up the logic, and enable programming truncation as a bit reduction
mode.

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Leo (Sunpeng) Li 2018-02-06 16:35:21 -05:00 • committed by Alex Deucher
commit 60c118c643