ncftp: clarify the NCFTP_RUN_AUTOCONF hook.

When I saw this patch it took me a while to figure out how/why it worked,
so let's make life easier for the eventual version bumper to understand
what's going on here.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>