mac80211: redesign auth/assoc

This is the second part of the auth/assoc redesign,
the mac80211 part. This moves the auth/assoc code
out of the work abstraction and into the MLME, so
that we don't flip channels all the time etc.

The only downside is that when we are associated,
we need to drop the association in order to create
a connection to another AP, but for most drivers
this is actually desirable and the ability to do
was never used by any applications. If we want to
implement resource reservation with FT-OTA, we'd
probably best do it with explicit R-O-C in wpa_s.

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