Namespace written twice on ONVIF service reference

After #3103 has been closed, I'm trying to add the reference to the ONVIF service using this command line:

```
dotnet svcutil https://www.onvif.org/ver10/events/wsdl/event.wsdl -n "*,MyNamespace"
```

Without the `-n` option, the service is correctly generated, but with that command, it generates:

```
public MyNamespace.MyNamespace.CreatePullPoint CreatePullPoint;
```

which is wrong.