dt-bindings: phy: qcom,qusb2: Add missing vdd-supply

Besides vdda-pll and vdda-phy-dpdm, vdd-supply is a required supply for
PHY digital circuit operation.  Add it for correctness and completeness.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210928022002.26286-2-shawn.guo@linaro.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>