ARM: dts: mx23: fix iio-hwmon support

commit e8e94ed6 upstream.

In order to get iio-hwmon support, the lradc must be declared as an
iio provider. So fix this issue by adding the #io-channel-cells property.
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Fixes: bd798f9c ("ARM: dts: mxs: Add iio-hwmon to mx23 soc")
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

arch/arm/boot/dts/imx23.dtsi

@@ -435,6 +435,7 @@ lradc: lradc@80050000 {
 				interrupts = <36 37 38 39 40 41 42 43 44>;
 				status = "disabled";
 				clocks = <&clks 26>;
+				#io-channel-cells = <1>;
 			};
 
 			spdif@80054000 {