packet-acn.c: Various cleanup

packet-acn.c: Various cleanup

1. Fix some typos (in hf_ field names and value_string values)
2. Fix an off-by-on error in blob calculation
3. Bugfix a few field lengths
4. Bugfix offset handling when adding ACN address

Change-Id: Id9e3d205b848ce3767b27ef1fcf02f7faae0be15
Reviewed-on: https://code.wireshark.org/review/20953
Reviewed-by: Michael Mann <mmann78@netscape.net>
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>