Deploy single-node etcd cluster with Ponsim

Change-Id: I784772df39c927f8ef64166e9e2d1de3c43aaf14
diff --git a/configs/seba-ponsim.yaml b/configs/seba-ponsim.yaml
index 2eaf656..d0b3b37 100644
--- a/configs/seba-ponsim.yaml
+++ b/configs/seba-ponsim.yaml
@@ -32,3 +32,6 @@
 netconfImage: 'voltha/voltha-netconf:latest'
 ofagentImage: 'voltha/voltha-ofagent:latest'
 vcliImage: 'voltha/voltha-cli:latest'
+etcd-operator:
+  etcdCluster:
+    size: 1