arm64: dts: renesas: r8a779f0: Add RWDT node

Add a device node for the RCLK Watchdog Timer (RWDT) on the Renesas
R-Car S4-8 (R8A779F0) SoC.

Extracted from a larger patch in the BSP by LUU HOAI.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGuenter Roeck <linux@roeck-us.net>
Reviewed-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/556a7f41bdadceecbe8b59b79ac7e9f592ca17a2.1642525158.git.geert+renesas@glider.be

arch/arm64/boot/dts/renesas/r8a779f0.dtsi

@@ -59,6 +59,16 @@
 		#size-cells = <2>;
 		ranges;
 
+		rwdt: watchdog@e6020000 {
+			compatible = "renesas,r8a779f0-wdt",
+				     "renesas,rcar-gen4-wdt";
+			reg = <0 0xe6020000 0 0x0c>;
+			clocks = <&cpg CPG_MOD 907>;
+			power-domains = <&sysc R8A779F0_PD_ALWAYS_ON>;
+			resets = <&cpg 907>;
+			status = "disabled";
+		};
+
 		cpg: clock-controller@e6150000 {
 			compatible = "renesas,r8a779f0-cpg-mssr";
 			reg = <0 0xe6150000 0 0x4000>;