Shorten a status text description.

Shorten a status text description.

Instead of just copying-and-pasting from 802.11, edit the description a
bit; this squelches a Coverity warning (it thought we might have
forgotten a comma in the list), and also means we don't quite print out
as much.

(If Table 8-37 "Status codes" in 802.11-2012 had names for *all* the
status codes, we could use the names instead of the explanatory text,
but, for some unknown reason, it doesn't.)