remove updating libvirt_nets, it has no effect

Change-Id: I5e4999b33419353627f7a127cbe61e8ebcb04148
Signed-off-by: ibarkan <ibarkan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/35694
Reviewed-by: Dan Kenigsberg <danken@redhat.com>