Modernize the 802.11w help text as support for 802.11w is
currently always compiled into hostapd/wpad and most of
the relevant wireless drivers support it well.
Add a cautionary note that some drivers do not fully support
it. Mention mwlwifi by name as it has several 802.11w bugs
open in upstream and its development has stopped.
Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>
e609ef0ef5