arm64: dts: qcom: sc7280: fix PCIe clock reference

The recent commit that dropped the PCIe PHY clock index failed to update
the PCIe node reference.

Fixes: 531c738f ("arm64: dts: qcom: sc7280: drop PCIe PHY clock index")
Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220707064222.15717-1-johan+linaro@kernel.org