arm64: dts: qcom: sc7280: Add device tree node for LLCC

Add a DT node for Last level cache (aka. system cache)
controller which provides control over the last level
cache present on SC7280 SoC.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/5bacaa8350e0d9553dccd623a15513590e795b47.1615832893.git.saiprakash.ranjan@codeaurora.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>