ARM: dts: r8a7779: Add device node for PRR

Add a device node for the Product Register, which provides SoC product
and revision information.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7779.dtsi

@@ -590,6 +590,11 @@
 		};
 	};
 
+	prr: chipid@ff000044 {
+		compatible = "renesas,prr";
+		reg = <0xff000044 4>;
+	};
+
 	sysc: system-controller@ffd85000 {
 		compatible = "renesas,r8a7779-sysc";
 		reg = <0xffd85000 0x0200>;