Set ipflush_onchange on gtw node of virtual-mcp-pike-ovs

This patch sets ipflush_onchange: True for interfaces of gateway node
of virtual-mcp-pike-ovs. Without this parameters Salt cannot remove address
from interfaces properly.

Change-Id: I534e7fc61e790b938c6a1435d133d563e24e1ae5
diff --git a/classes/cluster/virtual-mcp-pike-ovs/openstack/gateway.yml b/classes/cluster/virtual-mcp-pike-ovs/openstack/gateway.yml
index ae64c8f..b972747 100644
--- a/classes/cluster/virtual-mcp-pike-ovs/openstack/gateway.yml
+++ b/classes/cluster/virtual-mcp-pike-ovs/openstack/gateway.yml
@@ -43,6 +43,7 @@
           type: eth
         external_interface:
           enabled: true
+          ipflush_onchange: true
           name: ${_param:external_interface}
           mtu: ${_param:interface_mtu}
           proto: manual