drm/amdgpu: skip gpu_info fw loading on navi12

It's no longer required.

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2318


Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org