virt: move controller device to vmdevices.py

No real code changes

Change-Id: I941a76230fd5cc3c28495c5fa8526f8735bb51ef
Signed-off-by: Martin Polednik <mpolednik@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/29261
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Francesco Romani <fromani@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>