Set ipflush_onchange on gtw node of os-ha-ovs model

This patch sets ipflush_onchange: True for interfaces of gateway
node of os-ha-ovs model.
Without this parameters Salt cannot remove address from interfaces
properly.

Related-PROD: PROD-16793

Change-Id: I374a695f3f5d83b76b26d445615c71fc0b382e59
diff --git a/classes/cluster/os-aio-ovs/openstack/gateway.yml b/classes/cluster/os-aio-ovs/openstack/gateway.yml
index b167a48..8e12b86 100644
--- a/classes/cluster/os-aio-ovs/openstack/gateway.yml
+++ b/classes/cluster/os-aio-ovs/openstack/gateway.yml
@@ -23,18 +23,21 @@
           mtu: ${_param:interface_mtu}
         primary_interface:
           enabled: true
+          ipflush_onchange: true
           name: ${_param:primary_interface}
           mtu: ${_param:interface_mtu}
           proto: manual
           type: eth
         tenant_interface:
           enabled: true
+          ipflush_onchange: true
           name: ${_param:tenant_interface}
           mtu: ${_param:interface_mtu}
           proto: manual
           type: eth
         external_interface:
           enabled: true
+          ipflush_onchange: true
           name: ${_param:external_interface}
           mtu: ${_param:interface_mtu}
           proto: manual
@@ -82,4 +85,4 @@
       qos: ${_param:neutron_enable_qos}
       agent_mode: ${_param:neutron_gateway_agent_mode}
       backend:
-        tenant_network_types: ${_param:neutron_tenant_network_types}"
\ No newline at end of file
+        tenant_network_types: ${_param:neutron_tenant_network_types}"