drm/amd/display: [FW Promotion] Release 0.0.55

Add comments to better describe the function of different cmds
and parameters in the dmub interface

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