drm/amd/display: 3.2.126

DC version 3.2.126 brings improvements in multiple areas.
In summary, we highlight:

- DMUB fixes
- Firmware relase 0.0.55
- Expanded dmub_cmd documentation
- Enhancements in DCN30

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>