drm/amdgpu: add cyan_skillfish asic header files

This patch is to add cyan_skillfish asic header files.

Signed-off-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Zhan Liu <zhan.liu@amd.com>
Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Acked-by: Jun Lei <jun.lei@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>