dt-bindings: watchdog: rockchip: add rockchip,rk3128-wdt

Add rockchip,rk3128-wdt compatible string.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/a4da79fe-3449-6538-742f-790835ffe43a@gmail.com


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