dt-bindings: watchdog: aspeed-wdt: Add aspeed,reset-mask property

This property configures the Aspeed watchdog timer's reset mask, which
controls which peripherals are reset when the watchdog timer expires.
Some platforms require that certain devices be left untouched across a
reboot; aspeed,reset-mask can now be used to express such constraints.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230922104231.1434-5-zev@bewilderbeest.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>