arm64: dts: qcom: ipq8074-hk01: Add dummy supply for QMP USB3 PHY

Per QMP PHY bindings schema, 'vdda-phy-supply' and 'vdda-phy-supply' are
required for IPQ8074 QMP USB3 PHY.  Since supplies are not added in DTS
for this platform, add a dummy regulator as the supply to QMP USB3 PHY,
so that dtbs_check stops complaining the missing supplies.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210929034253.24570-10-shawn.guo@linaro.org