arm64: dts: microchip: add missing cache properties

As all level 2 and level 3 caches are unified, add required
cache-unified and cache-level properties to fix warnings like:

  sparx5_pcb125.dtb: l2-cache0: 'cache-level' is a required property

Link: https://lore.kernel.org/r/20230421223155.115339-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

arch/arm64/boot/dts/microchip/sparx5.dtsi

@@ -52,6 +52,8 @@
 		};
 		L2_0: l2-cache0 {
 			compatible = "cache";
+			cache-level = <2>;
+			cache-unified;
 		};
 	};