[Why]
Refactor ABM feature and implement inbox command for DMUB.

[How]
Implement the ioctl to send inbox command to DMUB.
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Leon Huang <Leon.Huang1@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>