cfg80211: don't overwrite privacy setting

When cfg80211 is instructed to connect, it always
uses the default WEP key for the privacy setting,
which clearly is wrong when using wpa_supplicant.
Don't overwrite the setting, and rely on it being
false when wpa_supplicant is not running, instead
set it to true when we have keys.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>