mgb4_i2c_init
rv = mgb4_i2c_init(&extender, mgbdev->i2c_adap, &extender_info, 8);
int mgb4_i2c_init(struct mgb4_i2c_client *client, struct i2c_adapter *adap,
rv = mgb4_i2c_init(&vindev->deser, vindev->mgbdev->i2c_adap, info,
rv = mgb4_i2c_init(ser, voutdev->mgbdev->i2c_adap, info, 8);