ARM: dts: qcom: sdx55: Add support for PCIe RC controller

The PCIe controller in SDX55 can act as the RC controller also. Let's
add support for it.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230308082424.140224-8-manivannan.sadhasivam@linaro.org