dt-binding: i2c: mt65xx: add vbus-supply property

Add vbus-supply property for mt65xx. The regulator can be passed into
core and turned off during suspend/sleep to reduce power consumption.
Signed-off-by: NHsin-Yi Wang <hsinyi@chromium.org>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NWolfram Sang <wsa@kernel.org>

Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt

@@ -32,6 +32,7 @@ Optional properties:
   - mediatek,have-pmic: platform can control i2c form special pmic side.
     Only mt6589 and mt8135 support this feature.
   - mediatek,use-push-pull: IO config use push-pull mode.
+  - vbus-supply: phandle to the regulator that provides power to SCL/SDA.
 
 Example: