The UEFI specification paragraph quoted above notes:
> The watchdog timer is only used during boot services. On successful
> completion of ExitBootServices() the watchdog timer is disabled.

Thus disabling the watchdog is _the_ only proper behavior. Adjust the
wording accordingly.

Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>