watchdog: aspeed: Add support for aspeed,reset-mask DT property

This property allows the device-tree to specify how the Aspeed
watchdog timer's reset mask register(s) should be set, so that
peripherals can be individually exempted from (or opted in to) being
reset when the watchdog timer expires.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230922104231.1434-6-zev@bewilderbeest.net


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