dt-bindings: wdt: Add ts72xx

Add DT binding for Technologic Systems TS-72xx watchdog.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20231212-ep93xx-v6-25-c307b8ac9aa8@maquefel.me


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