drm/amd/powerplay: add new smu9_driver_if.h for vega12 (v2)

Add driver firmware interface header.

v2: squash in interface updates.
Acked-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NEvan Quan <evan.quan@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>