dt-bindings: usb: dwc3: Add IPQ9574 compatible

* Document the IPQ9574 dwc3 compatible.

* Make power-domains as optional since IPQ9574 doesn't have GDSCs

Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Varadarajan Narayanan <[e-mail]>
Link: https://lore.kernel.org/r/27f[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/usb/qcom,dwc3.yaml

···
           - qcom,ipq6018-dwc3
           - qcom,ipq8064-dwc3
           - qcom,ipq8074-dwc3
+          - qcom,ipq9574-dwc3
           - qcom,msm8953-dwc3
           - qcom,msm8994-dwc3
           - qcom,msm8996-dwc3
···
   - "#address-cells"
   - "#size-cells"
   - ranges
-  - power-domains
   - clocks
   - clock-names
   - interrupts
···
         compatible:
           contains:
             enum:
+              - qcom,ipq9574-dwc3
               - qcom,msm8953-dwc3
               - qcom,msm8996-dwc3
               - qcom,msm8998-dwc3