ntpd -s option deprecated

I was seeing the following...

```
-s option no longer works and will be removed soon.
Please reconfigure to use constraints or trusted servers.
```

The -s option for ntpd has been deprecated. Seems like the -s option can simply be removed now (from start.sh) and defaults to expected/desired behaviour (?). See https://undeadly.org/cgi?action=article;sid=20191111075815 for more info.