ARM: dts: bcm: Align L2 cache-controller nodename with dtschema

Fix dtschema validator warnings like:
l2-cache@22000: $nodename:0:
'l2-cache@22000' does not match '^(cache-controller|cpu)(@[0-9a-f,]+)*$'

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Scott Branden <[e-mail]>
Signed-off-by: Florian Fainelli <[e-mail]>

arch/arm/boot/dts/bcm-cygnus.dtsi

···
 			      <0x20100 0x100>;
 		};
 
-		L2: l2-cache@22000 {
+		L2: cache-controller@22000 {
 			compatible = "arm,pl310-cache";
 			reg = <0x22000 0x1000>;
 			cache-unified;

arch/arm/boot/dts/bcm-hr2.dtsi

···
 			      <0x20100 0x100>;
 		};
 
-		L2: l2-cache@22000 {
+		L2: cache-controller@22000 {
 			compatible = "arm,pl310-cache";
 			reg = <0x22000 0x1000>;
 			cache-unified;

arch/arm/boot/dts/bcm-nsp.dtsi

···
 			      <0x20100 0x100>;
 		};
 
-		L2: l2-cache@22000 {
+		L2: cache-controller@22000 {
 			compatible = "arm,pl310-cache";
 			reg = <0x22000 0x1000>;
 			cache-unified;

arch/arm/boot/dts/bcm21664.dtsi

···
 		reg-io-width = <4>;
 	};
 
-	L2: l2-cache@3ff20000 {
+	L2: cache-controller@3ff20000 {
 		compatible = "arm,pl310-cache";
 		reg = <0x3ff20000 0x1000>;
 		cache-unified;