ARM: dts: vf610-zii-ssmb-dtu: Add voltage monitor DT node

Add a DT node for various voltage supply rails connected to SoC's ADC
for voltage monitoring purposes.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/vf610-zii-ssmb-dtu.dts

@@ -46,6 +46,14 @@ reg_vcc_3v3_mcu: regulator {
 		regulator-min-microvolt = <3300000>;
 		regulator-max-microvolt = <3300000>;
 	};
+
+	supply-voltage-monitor {
+		compatible = "iio-hwmon";
+		io-channels = <&adc0 8>, /* 12V_MAIN */
+			      <&adc0 9>, /* +3.3V    */
+			      <&adc1 8>, /* VCC_1V5  */
+			      <&adc1 9>; /* VCC_1V2  */
+	};
 };
 
 &adc0 {