arm64: dts: qcom: sm8250: Add PCIe support

Add PCIe support for Qcom SM8250 SoC. This SoC has 3 PCIe Gen 3
instances based on Designware IP, out of which PCIe0 has 1 lane support
and the rest have 2 lane support.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[DB: add ddrss_sf_tbu clock]
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210127234221.947306-2-dmitry.baryshkov@linaro.org


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