dt-bindings: watchdog: Add RK3506 compatible

The watchdog used on the RK3506 is still the same snps,dw-wdt compatible
one that is in use since the RK3066 days, so add the RK3506 to the
variant list.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Author: mmind

Documentation/devicetree/bindings/watchdog/snps,dw-wdt.yaml

@@ -28,6 +28,7 @@ properties:
               - rockchip,rk3328-wdt
               - rockchip,rk3368-wdt
               - rockchip,rk3399-wdt
+              - rockchip,rk3506-wdt
               - rockchip,rk3562-wdt
               - rockchip,rk3568-wdt
               - rockchip,rk3576-wdt