dt-bindings: display/panel: jh057n00900: Document power supply properties

Document the vcc-supply and iovcc-supply properties of the Rocktech
jh057n00900 panel.
Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/ec5ee11786036dc8826a3f8555cbb1dce4dbca25.1561542477.git.agx@sigxcpu.org

Documentation/devicetree/bindings/display/panel/rocktech,jh057n00900.txt

@@ -5,6 +5,9 @@ Required properties:
 - reg: DSI virtual channel of the peripheral
 - reset-gpios: panel reset gpio
 - backlight: phandle of the backlight device attached to the panel
+- vcc-supply: phandle of the regulator that provides the vcc supply voltage.
+- iovcc-supply: phandle of the regulator that provides the iovcc supply
+  voltage.
 
 Example:
 
@@ -14,5 +17,7 @@ Example:
 			reg = <0>;
 			backlight = <&backlight>;
 			reset-gpios = <&gpio3 13 GPIO_ACTIVE_LOW>;
+			vcc-supply = <&reg_2v8_p>;
+			iovcc-supply = <&reg_1v8_p>;
 		};
 	};