drm/amdgpu: add smu interface header for cyan_skilfish

Add smu11_driver_if_cyan_skillfish.h for cyan_skilfish.

Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>