Eliminate proto_tree_add_text from some dissectors.

Change-Id: I398e9cf4f6882e76644aa758e12c39a39159e95f
Reviewed-on: https://code.wireshark.org/review/3319
Petri-Dish: Michael Mann <mmann78@netscape.net>
Petri-Dish: Evan Huus <eapache@gmail.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>