mac80211: clear bssid on auth/assoc failure

commit 3d2abdfdf14f4d6decc2023708211e19b096f4ca upstream.

ifmgd->bssid wasn't cleared properly in some
auth/assoc failure cases, causing mac80211 and
the low-level driver to go out of sync.

Clear ifmgd->bssid on failure, and notify the driver.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>