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

Fix dtschema validator warnings like:
     l2-cache-controller@c4200000: $nodename:0:
         'l2-cache-controller@c4200000' does not match '^(cache-controller|cpu)(@[0-9a-f,]+)*$'
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20200626080626.4080-1-krzk@kernel.org

arch/arm/boot/dts/meson.dtsi

@@ -11,7 +11,7 @@ / {
 	#size-cells = <1>;
 	interrupt-parent = <&gic>;
 
-	L2: l2-cache-controller@c4200000 {
+	L2: cache-controller@c4200000 {
 		compatible = "arm,pl310-cache";
 		reg = <0xc4200000 0x1000>;
 		cache-unified;