netconf: privatize inRollback

inRollback is not part of the external setupNetworks api. Thus, it
is wise to be coherent and prefix it with '_'.

Change-Id: I6bcf98cb587c99366173d0a2994444b6370c9778
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/21868
Reviewed-by: Assaf Muller <amuller@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>