nvif_object_sclass_get
ret = n = nvif_object_sclass_get(disp, &sclass);
int nvif_object_sclass_get(struct nvif_object *, struct nvif_sclass **);
cnt = nvif_object_sclass_get(object, &sclass); \
ret = nvif_object_sclass_get(&chan->chan->user, &sclass);
ret = nvif_object_sclass_get(&chan->chan->user, &sclass);
ret = n = nvif_object_sclass_get(&device->object, &sclass);