drm/amd/powerplay: add new ppsmc header for smu11 (v2)

This header will be used for smc message handling.

v2: add a license to the top of the header file (Alex)

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>