RSVP checksum is not required if integrity object is present

Bug: 10219
Change-Id: I2da62ee184327b2bc42a264e1782db927460f5cf
Reviewed-on: https://code.wireshark.org/review/2773
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>