drm/amdgpu: make audio dev's D-state transition PMFW-aware

To correctly kick into BACO state, the audio dev's D-state
transition(D0->D3) needs to be PMFW-aware. So, if the audio
dev entered D3 state prior to our driver, we need to bring
it back to D0 state and make sure there will be a D-state
transition on runpm suspend.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>