ARM: dts: r8a7793: Add L2 cache-controller node

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

The L2 cache for the Cortex-A15 CPU cores is 1 MiB large (organized as
64 KiB x 16 ways).
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7793.dtsi

@@ -51,6 +51,7 @@ cpu0: cpu@0 {
 					   < 937500 1000000>,
 					   < 750000 1000000>,
 					   < 375000 1000000>;
+			next-level-cache = <&L2_CA15>;
 		};
 	};
 
@@ -73,6 +74,12 @@ cooling-maps {
 		};
 	};
 
+	L2_CA15: cache-controller@0 {
+		compatible = "cache";
+		cache-unified;
+		cache-level = <2>;
+	};
+
 	gic: interrupt-controller@f1001000 {
 		compatible = "arm,gic-400";
 		#interrupt-cells = <3>;