opencontrail: don't mix with vgw on devstack
opencontrail: don't mix with vgw on devstack

When vgw is used it has also type of vhost and it might be discovered
first in place of vhost0. In that case tap interfaces will not be linked
in the topology.

Change-Id: I4b25353087698869d4814ad39d09aad56595dca5

safchain/skydive,safchain/skydive,skydive-project/skydive,skydive-project/skydive,safchain/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,safchain/skydive,safchain/skydive,safchain/skydive,safchain/skydive,skydive-project/skydive,safchain/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive