drm/amdgpu: implement GFX 9.0 support (v2)

Add support for gfx v9.0.

v2: update golden settings from Ken

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Ken Wang <Qingqing.Wang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>