network: reuse netinfo.ports()

Change-Id: I77e542cb0982e792e29d092f9e911cf74d910d36
Signed-off-by: huntxu <mhuntxu@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/12503
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>