ARM: dts: r8a7740: Fix W=1 dtc warnings

Warning (unit_address_vs_reg): Node /cache-controller has a reg or ranges property, but no unit name
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7740.dtsi

@@ -39,7 +39,7 @@ gic: interrupt-controller@c2800000 {
 		      <0xc2000000 0x1000>;
 	};
 
-	L2: cache-controller {
+	L2: cache-controller@f0100000 {
 		compatible = "arm,pl310-cache";
 		reg = <0xf0100000 0x1000>;
 		interrupts = <GIC_SPI 84 IRQ_TYPE_LEVEL_HIGH>;