arm64: dts: qcom: sc8180x: Fix eDP PHY power-domains

The (e)DP PHYs are powered by the MX line, not through the MDSS GDSC.
Fix that up.

Fixes: 494dec9b ("arm64: dts: qcom: sc8180x: Add display and gpu nodes")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20231230-topic-8180_more_fixes-v1-5-93b5c107ed43@linaro.org


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