ARM: dts: Change iio_hwmon nodes to use hypen in node names

Change iio_hwmon nodes to use hypen in node names instead of
underscore.
Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/iio/iio-bindings.txt

@@ -82,7 +82,7 @@ vdd channel is connected to output 0 of the &ref device.
 
 	...
 
-	iio_hwmon {
+	iio-hwmon {
 		compatible = "iio-hwmon";
 		io-channels = <&adc 0>, <&adc 1>, <&adc 2>,
 			<&adc 3>, <&adc 4>, <&adc 5>,

arch/arm/boot/dts/imx23.dtsi

@@ -569,7 +569,7 @@ usb0: usb@80080000 {
 		};
 	};
 
-	iio_hwmon {
+	iio-hwmon {
 		compatible = "iio-hwmon";
 		io-channels = <&lradc 8>;
 	};

arch/arm/boot/dts/imx28.dtsi

@@ -1256,7 +1256,7 @@ etn_switch: switch@800f8000 {
 		};
 	};
 
-	iio_hwmon {
+	iio-hwmon {
 		compatible = "iio-hwmon";
 		io-channels = <&lradc 8>;
 	};