dt-bindings: regulator: qcom,usb-vbus-regulator: Add PM7250B compatible

The VBUS register block on the PM6150 PMIC shares the design with the
PM8150B one. Define corresponding compatible string, having the
qcom,pm8150b-vbus-reg as a fallback.

Signed-off-by: Luca Weiss <[e-mail]>
Reviewed-by: Bryan O'Donoghue <[e-mail]>
Link: https://msgid.link/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/qcom,usb-vbus-regulator.yaml

···
           - enum:
               - qcom,pm4125-vbus-reg
               - qcom,pm6150-vbus-reg
+              - qcom,pm7250b-vbus-reg
               - qcom,pmi632-vbus-reg
           - const: qcom,pm8150b-vbus-reg