arm64: dts: qcom: sc8280xp: fix DP PHY node unit addresses

Fix up the DP PHY node which had the wrong unit address.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220708072556.4687-1-johan+linaro@kernel.org