arm64: dts: qcom: sa8295p-adp: enable PCIe

The SA8295P-ADP has up to four PCIe interfaces implemented by three or
four controllers: PCIe2A, PCIe3A/PCIe3B and PCIe4.

PCIe2 is used in x4 mode, while PCIe3 can be used in either x2 or x4
mode. Enable both PCIe3A and PCI3B in x2 mode for now.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221110103558.12690-3-johan+linaro@kernel.org