commit 8878d854 upstream.

topaz is actually gmc7.
Reviewed-by: Ken Wang <Qingqing.Wang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[ kamal: backport to 4.2-stable: context; merged gmc_v8_0_hw_init() delta from
  ad32152e "drm/amdgpu: no need to load MC firmware on fiji" ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>