Solved bug in IETF L2VPN Service Handler

- service was created instead of updated.

src/compute/service/rest_server/nbi_plugins/ietf_l2vpn/L2VPN_SiteNetworkAccesses.py

@@ -125,7 +125,7 @@ def process_list_site_network_access(
     for site_network_access in request_data['ietf-l2vpn-svc:site-network-access']:
         try:
             service_request = process_site_network_access(context_client, site_network_access)
-            service_reply = service_client.CreateService(service_request)
+            service_reply = service_client.UpdateService(service_request)
             if service_reply != service_request.service_id: # pylint: disable=no-member
                 raise Exception('Service update failed. Wrong Service Id was returned')
         except Exception as e: # pylint: disable=broad-except