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: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAnthony Koo <Anthony.Koo@amd.com>
Acked-by: NEryk Brol <eryk.brol@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>