drm/amdgpu/discovery: Set GC family for GC 11.0 IP

Set GC family for GC 11.0 IPs.

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>