E-LMI: add what seems to be a missing break (Coverity CID 1245648)

Change-Id: I6b35ea96fba142bdabf17d3fc3f9db23dc390d31
Reviewed-on: https://code.wireshark.org/review/4613
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>