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

Documentation/devicetree/bindings/phy/qcom,qusb2-phy.yaml

@@ -51,6 +51,10 @@ properties:
       - const: ref
       - const: iface
 
+  vdd-supply:
+    description:
+      Phandle to 0.9V regulator supply to PHY digital circuit.
+
   vdda-pll-supply:
     description:
       Phandle to 1.8V regulator supply to PHY refclk pll block.
@@ -157,6 +161,7 @@ required:
   - "#phy-cells"
   - clocks
   - clock-names
+  - vdd-supply
   - vdda-pll-supply
   - vdda-phy-dpdm-supply
   - resets
@@ -175,6 +180,7 @@ examples:
                  <&gcc GCC_RX1_USB2_CLKREF_CLK>;
         clock-names = "cfg_ahb", "ref";
 
+        vdd-supply = <&pm8994_l28>;
         vdda-pll-supply = <&pm8994_l12>;
         vdda-phy-dpdm-supply = <&pm8994_l24>;