EAP: Fixup the check for Code value.

[tcpdump] / tests / hoobr_bfd_print.out

    1  [Invalid header: len(808464432) > 262144]
    2  [Invalid header: len(808464432) > 262144]
    3  05:27:12.808464432 IP truncated-ip - 14 bytes missing! 48.48.48.48.12336 > 48.48.48.48.3785: BFD, Echo, length: 12308