engine:  Error code 23 when invoking Setup Networks

In case the network is not in sync, it shouldn't override the interface's
vlan id.

Bug-Url: https://bugzilla.redhat.com/1115001
Change-Id: Iac0252076e8fa8704ed6c5257aeb5824d71470c5
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>