arm64: dts: sc7180: Add minimal dts/dtsi files for SC7180 soc

Add skeletal sc7180 SoC dtsi and idp board dts files.

Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Co-developed-by: Taniya Das <tdas@codeaurora.org>
Signed-off-by: Taniya Das <tdas@codeaurora.org>
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Link: https://lore.kernel.org/r/20191108092824.9773-3-rnayak@codeaurora.org


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