fix a PEP 8 issue in vdsm/configNetwork.py

Change-Id: Idc05505b84197fdebc919e4647ef757b295f52a2
Signed-off-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>
Reviewed-on: http://gerrit.ovirt.org/12744
Tested-by: oVirt Jenkins CI Server
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>