For s390-ccw-virtio machines the default bus type is set to ccw.
Specifing an address element allows to override the default.
Signed-off-by: NBoris Fiuczynski <fiuczy@linux.vnet.ibm.com>
Reviewed-by: NJason J. Herne <jjherne@us.ibm.com>
Reviewed-by: NStefan Zimmermann <stzi@linux.vnet.ibm.com>