mac80211: remove unused driver ops

The driver operations set_ieee8021x(), set_port_auth() and
set_privacy_invoked() are not used by any drivers, except
set_privacy_invoked() they aren't even used by mac80211.
Remove them at least until we need to support drivers with
mac80211 that require getting this information.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>