dt-bindings: watchdog: marvell GTI system watchdog driver

Add binding documentation for the Marvell GTI system
watchdog driver.

Signed-off-by: Bharat Bhushan <bbhushan2@marvell.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230803032523.6242-1-bbhushan2@marvell.com


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