If it is not there yet, it might appear later.
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
        adapter = of_find_i2c_adapter_by_node(adapter_np);
        if (!adapter) {
                dev_err(mux->dev, "Cannot find parent bus\n");
-               return -ENODEV;
+               return -EPROBE_DEFER;
        }
        mux->pdata->parent_bus_num = i2c_adapter_id(adapter);
        put_device(&adapter->dev);
        if (!mux->parent) {
                dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
                        mux->pdata->parent_bus_num);
-               ret = -ENODEV;
+               ret = -EPROBE_DEFER;
                goto err;
        }