airo: queue SIOCSIWAUTH-requested auth mode change for next commit

Code was clearly wrong, plus callers expect the mode change to happen as
soon as possible, not dropped on the floor until the next time some
other config value changes and a commit happens.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>