orinoco: fix TKIP countermeasure behaviour

Enable the port when disabling countermeasures, and disable it on
enabling countermeasures.

This bug causes the response of the system to certain attacks to be
ineffective.

It also prevents wpa_supplicant from getting scan results, as
wpa_supplicant disables countermeasures on startup - preventing the
hardware from scanning.

wpa_supplicant works with ap_mode=2 despite this bug because the commit
handler re-enables the port.

The log tends to look like:

State: DISCONNECTED -> SCANNING
Starting AP scan for wildcard SSID
Scan requested (ret=0) - scan timeout 5 seconds
EAPOL: disable timer tick
EAPOL: Supplicant port status: Unauthorized
Scan timeout - try to get results
Failed to get scan results
Failed to get scan results - try scanning again
Setting scan request: 1 sec 0 usec
Starting AP scan for wildcard SSID
Scan requested (ret=-1) - scan timeout 5 seconds
Failed to initiate AP scan.

Reported by: Giacomo Comes <comes@naic.edu>
Signed-off by: David Kilroy <kilroyd@googlemail.com>
Cc: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>