get rid of type_2 in most places

type_2 is nothing else but the request type in a setup packet
this is already stored in the conversation / transaction structure

Change-Id: I4dda7aff423eb1b6174a1a630d57e126662abed4
Reviewed-on: https://code.wireshark.org/review/3598
Petri-Dish: Martin Kaiser <wireshark@kaiser.cx>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>