ARM: dts: mxs: Add iio-hwmon to mx23 soc

This allows to read the SoC on-die temperature sensor available on the LRADC by
using:
 cat /sys/class/hwmon/hwmon0/device/temp1_input
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx23.dtsi

@@ -428,7 +428,7 @@
 				status = "disabled";
 			};
 
-			lradc@80050000 {
+			lradc: lradc@80050000 {
 				compatible = "fsl,imx23-lradc";
 				reg = <0x80050000 0x2000>;
 				interrupts = <36 37 38 39 40 41 42 43 44>;
@@ -526,4 +526,9 @@
 			status = "disabled";
 		};
 	};
+
+	iio_hwmon {
+		compatible = "iio-hwmon";
+		io-channels = <&lradc 8>;
+	};
 };