The essid wireless extension does deadlock against the assoc mutex,
as we don't unlock the assoc mutex when flushing the workqueue, which
also holds the lock.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>