Fix typo in Ice grid template to enable remote JMX connections

To test the change (assuming a running server):
- fill in `jmxhost` parameter with your server's IP address in $OMERO_HOME/etc/grid/templates.xml
- run `omero admin deploy jmx`
- check for listening java process on TCP port 3001
- connect JMX agent - eg. `jconsole <server_ip>:3001`