ARM: dts: vexpress: add missing cache properties

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

  vexpress-v2p-ca5s.dtb: cache-controller@2c0f0000: 'cache-unified' is a required property
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230423150837.118466-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

arch/arm/boot/dts/vexpress-v2p-ca5s.dts

@@ -132,6 +132,7 @@ L2: cache-controller@2c0f0000 {
 		reg = <0x2c0f0000 0x1000>;
 		interrupts = <0 84 4>;
 		cache-level = <2>;
+		cache-unified;
 	};
 
 	pmu {