arm64: dts: r8a7796: Add device node for PRR

Add a device node for the Product Register, which provides SoC product
and revision information.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7796.dtsi

@@ -243,6 +243,11 @@
 			#power-domain-cells = <0>;
 		};
 
+		prr: chipid@fff00044 {
+			compatible = "renesas,prr";
+			reg = <0 0xfff00044 0 4>;
+		};
+
 		sysc: system-controller@e6180000 {
 			compatible = "renesas,r8a7796-sysc";
 			reg = <0 0xe6180000 0 0x0400>;