The driver supports setting watchdog timeout, system reset
and querying reset reason. Disabling watchdog isn't possible
in hardware, thus users should either only enable it before
boot or have the poller take care of feeding it.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>