cfg80211/nl80211: add a port authorized event

Add an event that indicates that a connection is authorized
(i.e. the 4 way handshake was performed by the driver). This event
should be sent by the driver after sending a connect/roamed event.

This is useful for networks that require 802.1X authentication.
In cases that the driver supports 4 way handshake offload, but the
802.1X authentication is managed by user space, the driver needs to
inform user space right after the 802.11 association was completed
so user space can initialize its 802.1X state machine etc.
However, it is also possible that the AP will choose to skip the
802.1X authentication (e.g. when PMKSA caching is used) and proceed
with the 4 way handshake immediately. In this case the driver needs
to inform user space that 802.1X authentication is no longer required
(e.g. to prevent user space from disconnecting since it did not get
any EAPOLs from the AP).

This is also useful for roaming, in which case it is possible that
the driver used the Fast Transition protocol so 802.1X is not
required.

Since there will now be a dedicated notification indicating that the
connection is authorized, the authorized flag can be removed from the
roamed event. Drivers can send the new port authorized event right
after sending the roamed event to indicate the new AP is already
authorized. This therefore reserves the old PORT_AUTHORIZED attribute.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>