drm/amdgpu: add status checking after fw is loaded

The status field must be 0 after FW is loaded.

Signed-off-by: Huang Rui <ray.huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>