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

  k3-am6528-iot2050-basic-pg2.dtb: l3-cache0: 'cache-unified' is a required property
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20230421223143.115099-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Vignesh Raghavendra <vigneshr@ti.com>