ARM: dts: r8a7794: Add L2 cache-controller node

Add a device node for the L2 cache, and link the CPU nodes to it.

The L2 cache for the Cortex-A7 CPU cores is 512 KiB large (organized as
64 KiB x 8 ways).
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7794.dtsi

@@ -40,6 +40,7 @@ cpu0: cpu@0 {
 			compatible = "arm,cortex-a7";
 			reg = <0>;
 			clock-frequency = <1000000000>;
+			next-level-cache = <&L2_CA7>;
 		};
 
 		cpu1: cpu@1 {
@@ -47,9 +48,16 @@ cpu1: cpu@1 {
 			compatible = "arm,cortex-a7";
 			reg = <1>;
 			clock-frequency = <1000000000>;
+			next-level-cache = <&L2_CA7>;
 		};
 	};
 
+	L2_CA7: cache-controller@1 {
+		compatible = "cache";
+		cache-unified;
+		cache-level = <2>;
+	};
+
 	gic: interrupt-controller@f1001000 {
 		compatible = "arm,gic-400";
 		#interrupt-cells = <3>;