drm/amdgpu/powerplay: add header file for smu10. (v2)

Headers define the driver/fw interface for smu10.

v2: squash in updates (Alex)

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