[PATCH] ieee80211: common wx auth code

This patch creates two functions ieee80211_wx_set_auth and
ieee80211_wx_get_auth that can be used by drivers for the wireless
extension handlers instead of writing their own, if the implementation
should be software only.

These patches enable using bcm43xx devices with WPA and this seems (as
far as I can tell) to be the only difference between the stock ieee80211
and softmac's ieee80211 left.

Signed-Off-By: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>