ARM: dts: sun7i: set proper lradc vref on OLinuXino Lime2

The lradc's analog reference voltage is set to 3.0 volt in the
hardware. This is more or less set in copper for at least lradc0. Set the
property in the dts to ensure the lradc is referenced properly.
Signed-off-by: NOlliver Schinagl <oliver@schinagl.nl>
Signed-off-by: NPriit Laes <plaes@plaes.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@bootlin.com>

arch/arm/boot/dts/sun7i-a20-olinuxino-lime2.dts

@@ -154,6 +154,10 @@
 	};
 };
 
+&lradc {
+	vref-supply = <&reg_vcc3v0>;
+};
+
 &mmc0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&mmc0_pins_a>;