cfg80211: don't optimise wext calls too much

In the wext code I tried to not reconnect all the time
when the user wasn't really sure what they were doing,
like setting the BSSID back to the same value it was.
However, this optimisation should only be done while
associated so that setting the BSSID back to the same
value that it was actually triggers a new association
if not currently associated. To achieve, that, put the
relevant code into the !IDLE case instead.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Kalle Valo <kalle.valo@iki.fi>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>