DCERPC DFS: Remove from Dirty PIDL list

Change-Id: I87bd196d1c4ba14d9af6d174754b37d2b4d772c8
Reviewed-on: https://code.wireshark.org/review/4527
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>