drm/amdgpu: Free resources of bo_list when idr_alloc fails

Signed-off-by: Alex Xie <AlexBin.Xie@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Christian <König&lt;christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>