Add required cache-level and cache-unified properties to fix warnings
like:

  qdu1000-idp.dtb: l3-cache: 'cache-unified' is a required property
  qdu1000-idp.dtb: l2-cache: 'cache-level' is a required property
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230416101134.95686-3-krzysztof.kozlowski@linaro.org