arm64: dts: qcom: qcs404: Add PCIe related nodes

The QCS404 has a PCIe2 PHY and a Qualcomm PCIe controller, define these
to for the platform.

Reviewed-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>