mrcpv2: Fixed a memory leakage.

Moved mrcpv2_tcp_range to proto_reg_handoff and removed the unused
range_empty() init.

Change-Id: I0bb704db62299c9b3f54e2924162738bf7290ab6
Reviewed-on: https://code.wireshark.org/review/5156
Reviewed-by: Evan Huus <eapache@gmail.com>
Petri-Dish: Evan Huus <eapache@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>