Don't sync uninstantiated instances

Change-Id: I6e5fe2e39fe4c41ad9a8745a47cbba50eae40afe
diff --git a/xos/synchronizer/steps/sync_host.yaml b/xos/synchronizer/steps/sync_host.yaml
index 8bc442f..55dc70b 100644
--- a/xos/synchronizer/steps/sync_host.yaml
+++ b/xos/synchronizer/steps/sync_host.yaml
@@ -5,3 +5,4 @@
   tasks:
   - name: Add host entry for fabric
     command: curl -sS --user onos:rocks -X POST -HContent-Type:application/json -d '{{ rest_json }}' http://{{ rest_hostname }}:{{ rest_port }}/{{ rest_endpoint }}
+