drm/amdgpu: add smu_v11_8_pmfw header for cyan_skilfish

Add smu_v11_8_pmfw.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>