Remove `ntp_make_packet` since it is dead code (#681)
Remove `ntp_make_packet` since it is dead code (#681)

The function is not called anywhere. The module's make_packet uses `udp_make_packet`.
The type of `ntp_make_packet` is also not compatible with `probe_make_packet_cb` any longer. For example the `size_t *buf_len` argument is missing.

https://github.com/zmap/zmap/pull/681
zmap/zmap,zmap/zmap,zmap/zmap