drm/amd/powerplay: implement new funcs to check current states for tonga.

Implement the new callbacks for tonga.

Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>