ARM: dts: sun8i: r40: add watchdog device node

The R40 SoC has a watchdog like the one on A20, in the timer memory zone
(which is also the same on A20).

Add the device tree node for it.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>

arch/arm/boot/dts/sun8i-r40.dtsi

@@ -229,6 +229,11 @@ uart0_pb_pins: uart0-pb-pins {
 			};
 		};
 
+		wdt: watchdog@1c20c90 {
+			compatible = "allwinner,sun4i-a10-wdt";
+			reg = <0x01c20c90 0x10>;
+		};
+
 		uart0: serial@1c28000 {
 			compatible = "snps,dw-apb-uart";
 			reg = <0x01c28000 0x400>;