arm64: dts: qcom: sm6375: Add CPUCP L3 node

Configure the L3 cache DVFS scaler within the CPUCP block to allow
for dynamic frequency switching.

Reviewed-by: Sibi Sankar <quic_sibis@quicinc.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230303-topic-sm6375_features0_dts-v2-9-708b8191f7eb@linaro.org