thunderbolt: Add authorized value to the KOBJ_CHANGE uevent

For security reasons, we would like to monitor and track when the
Thunderbolt devices are authorized and deauthorized (i.e. when the
Thunderbolt sysfs "authorized" attribute changes). Currently the
userspace gets a udev change notification when there is a change, but
the state may have changed (again) by the time we look at the authorized
attribute in sysfs. So an authorization event may go unnoticed. Thus
make it easier by informing the actual change (new value of authorized
attribute) in the udev change notification.

The change is included as a key value "authorized=<val>" where <val>
is the new value of sysfs attribute "authorized", and is described at
Documentation/ABI/testing/sysfs-bus-thunderbolt under
/sys/bus/thunderbolt/devices/.../authorized.

Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>