voip_calls: Fix MTP3 & SUA taps.

Fix the registration of M3UA and remove SUA.

Change-Id: I7431c980403730bf6e53fa5be84fe85f15c106de
Reviewed-on: https://code.wireshark.org/review/5375
Reviewed-by: Gerald Combs <gerald@wireshark.org>
(cherry picked from commit ae51d109bbf64d02c39a684228ec193f287f5110)
Reviewed-on: https://code.wireshark.org/review/5376