watchdog: sama5d4: readout initial state

Readout the AT91_WDT_MR bit at probe so that it becomes possible to get the
pre-userspace handler working.

Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230819084726.11037-1-othacehe@gnu.org


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>