drm/amdgpu/powerplay: add smu11 driver interface for arcturus. (v2)

add smu11_driver_if_arcturus.h file.

v2: add license, fix header guard (Alex)

Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>