arm64: dts: r8a7795: Add L2 cache-controller nodes

Add device nodes for the L2 caches, and link the CPU node to its L2
cache node.

The L2 cache for the Cortex-A57 CPU cores is 2 MiB large (organized as
128 KiB x 16 ways).
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7795.dtsi

@@ -39,6 +39,7 @@ a57_0: cpu@0 {
 			compatible = "arm,cortex-a57", "arm,armv8";
 			reg = <0x0>;
 			device_type = "cpu";
+			next-level-cache = <&L2_CA57>;
 			enable-method = "psci";
 		};
 
@@ -46,22 +47,29 @@ a57_1: cpu@1 {
 			compatible = "arm,cortex-a57","arm,armv8";
 			reg = <0x1>;
 			device_type = "cpu";
+			next-level-cache = <&L2_CA57>;
 			enable-method = "psci";
 		};
 		a57_2: cpu@2 {
 			compatible = "arm,cortex-a57","arm,armv8";
 			reg = <0x2>;
 			device_type = "cpu";
+			next-level-cache = <&L2_CA57>;
 			enable-method = "psci";
 		};
 		a57_3: cpu@3 {
 			compatible = "arm,cortex-a57","arm,armv8";
 			reg = <0x3>;
 			device_type = "cpu";
+			next-level-cache = <&L2_CA57>;
 			enable-method = "psci";
 		};
 	};
 
+	L2_CA57: cache-controller@0 {
+		compatible = "cache";
+	};
+
 	extal_clk: extal {
 		compatible = "fixed-clock";
 		#clock-cells = <0>;