6LoWPAN: fix dissection when using multicast address compression

Also update the value_string arrays with the various SAM/DAM combinations

Bug: 10426
Change-Id: I87f13c29f42770ec655d85e2247b847bfe28e3ba
Reviewed-on: https://code.wireshark.org/review/3915
Petri-Dish: Pascal Quantin <pascal.quantin@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Evan Huus <eapache@gmail.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>