nl80211: Add IEEE 802.1X PAE control for station mode

Add a new NL80211_ATTR_CONTROL_PORT flag for NL80211_CMD_ASSOCIATE to
allow user space to indicate that it will control the IEEE 802.1X port
in station mode. Previously, mac80211 was always marking the port
authorized in station mode. This was enough when drop_unencrypted flag
was set. However, drop_unencrypted can currently be controlled only
with WEXT and the current nl80211 design does not allow fully secure
configuration. Fix this by providing a mechanism for user space to
control the IEEE 802.1X port in station mode (i.e., do the same that
we are already doing in AP mode).

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>