arm64: dts: qcom: sm8150: add ref clock to PCIe PHYs

Follow the rest of the platforms and add "ref" clocks to both PCIe PHYs
found on the Qualcomm SM8150 platform.

Fixes: a1c86c68 ("arm64: dts: qcom: sm8150: Add PCIe nodes")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20230820142035.89903-15-dmitry.baryshkov@linaro.org


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