Cut paste bug fix in Remote Syslog DHCP events

This version for 2.1 branch.
apinger is repeated here from the code above, but it should be dhcp.
Forum https://forum.pfsense.org/index.php?topic=73734.0
Selecting to remote syslog "Gateway Monitor events" would also switch on "DHCP service events" unintentionally.
Merge pull request #1119 from phil-davis/patch-4
Resolver has no option for remote syslog, remove wrong copy/paste that was adding it when apinger was enabled