The workqueue provided by mac80211 should not be used for
scheduled tasks that acquire the RTNL lock. This could be done
when the driver uses the function ieee80211_iterate_active_interfaces()
within the scheduled work. Such behavior will end in locking
dependencies problems when an interface is being removed.

This patch will add a notification about the RTNL locking and
the mac80211 workqueue to prevent driver developers from
blindly using it.
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Acked-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>