arm64: dts: qcom: sm6350: Add GCC node

Add and configure GCC node to allow for referencing GCC-controlled clocks
in other nodes.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210923162204.21752-5-konrad.dybcio@somainline.org