drm/amdgpu/powerplay: add smu support for navy_flounder

Now navy_flounder will reuse the smu11 driver_if header and ppt
functions for sienna_cichlid. Later navy_flounder can maintain
its own version if the compatibility is broken.

Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>