arm64: dts: qcom: sdm660: Make the DTS an overlay on top of 630

There is SO MUCH common code between these two SoCs that it makes
no sense to keep what is essentially a duplicate of 630.dtsi. Instead,
it's better to just change the things that differ.

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Link: https://lore.kernel.org/r/20210728222542.54269-25-konrad.dybcio@somainline.org


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