Eliminate proto_tree_add_text from IP dissectors

Change-Id: I81fc364cbff3c5b305d61b2d444bf8599fbd19e7
Reviewed-on: https://code.wireshark.org/review/4631
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>