The ports are 100Gb but must be "broken out" to a single 40Gb port.
FortyGig ports show up as <module>/<port>/1, which is different than
what the "nybbleEncoded" feature expects.

XXX this seriously needs to be revisited to see if there is a generalization
to be made; right now I just don't want to break other users of this module
(i.e., Clemson) by doing something rash.