arm64: dts: qcom: sc7280: Add pcie clock support

Add pcie clock phandle for sc7280 SoC.

Signed-off-by: Prasad Malisetty <pmaliset@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/1637060508-30375-3-git-send-email-pmaliset@codeaurora.org