[MAC80211]: STA reassociation improvements

My cheapy D-Link AP behaves strangely w.r.t reassociations.

The following sequence of commands causes me to lose association and to be
unable to regain it:

	ifconfig eth8 down
	ifconfig eth8 up
	iwconfig eth8 essid <x>

This is because mac80211 tries to reassociate, rather than just associate.
My AP replies with an association response (not a reassociation response...)
denying the association with code 12: "Association denied due to reason
outside the scope of this standard"

mac80211 tries this reassociation another 4 times or so before finally giving
up.

I see 2 problems here:
 1. bringing the interface down and up again should be resetting interface state
    i.e. after the interface is brought down, it should have no memory of if or
         where it was previously associated
 2. after the first reassociation fails, mac80211 should fall back to
    standard association for the next attempt

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>