ARM: dts: r8a7790: 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/arm/boot/dts/r8a7790.dtsi

@@ -1471,6 +1471,11 @@ R8A7790_CLK_SCU_SRC4 R8A7790_CLK_SCU_SRC3 R8A7790_CLK_SCU_SRC2 R8A7790_CLK_SCU_S
 		};
 	};
 
+	prr: chipid@ff000044 {
+		compatible = "renesas,prr";
+		reg = <0 0xff000044 0 4>;
+	};
+
 	sysc: system-controller@e6180000 {
 		compatible = "renesas,r8a7790-sysc";
 		reg = <0 0xe6180000 0 0x0200>;