dt-bindings: watchdog: Add Cirrus EP93x

Add device tree bindings for the Cirrus Logic EP93xx watchdog block
used in these SoCs.

Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240909-ep93xx-v12-10-e86ab2423d4b@maquefel.me


Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>