mac80211: rework MLME for multiple authentications

Sit tight. This shakes up the world as you know
it. Let go of your spaghetti tongs, they will no
longer be required, the horrible statemachine in
net/mac80211/mlme.c is no more...

With the cfg80211 SME mac80211 now has much less
to keep track of, but, on the other hand, for FT
it needs to be able to keep track of at least one
authentication being in progress while associated.
So convert from a single state machine to having
small ones for all the different things we need to
do. For real FT it will still need work wrt. PS,
but this should be a good step.

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