MIPv6: Mobility Header Link Layer Address is parsed incorrectly

Looking at RFC 5568 (http://tools.ietf.org/html/rfc5568#section-6.4.3)
It says that the Link-Layer Address (LLA) Option, should have an address right after the option code

Bug:10006
Bug:10627
Change-Id: I6fcd98a7c9896862e4c9547b945cf3848daaf474
Reviewed-on: https://code.wireshark.org/review/5075
Reviewed-by: Anders Broman <a.broman58@gmail.com>