cfg80211: sme: deauthenticate on assoc failure

When the in-kernel SME gets an association failure from
the AP we don't deauthenticate, and thus get into a very
confused state which will lead to warnings later on. Fix
this by actually deauthenticating when the AP indicates
an association failure.

(Brought to you by the hacking session at Kernel Summit 2009 in Tokyo,
Japan. -- JWL)

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