BGP : Update BGP-LS Attribute + Display NEXT_HOP

From IANA page: http://www.iana.org/assignments/bgp-parameters/bgp-parameters.xhtml

Change-Id: Ibc85dccee94aa69306c88b48d680e48fede08f2e
Reviewed-on: https://code.wireshark.org/review/5965
Reviewed-by: Michael Mann <mmann78@netscape.net>