ARM: dts: meson8m2: mxiii-plus: add iio-hwmon for the chip temperature

SAR ADC enabled channel 8 can be used to measure the chip temperature.
This can be made available to the hwmon subsystem by using iio-hwmon.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

arch/arm/boot/dts/meson8m2-mxiii-plus.dts

@@ -44,6 +44,11 @@ button-function {
 		};
 	};
 
+	iio-hwmon {
+		compatible = "iio-hwmon";
+		io-channels = <&saradc 8>;
+	};
+
 	vcc_3v3: regulator-vcc3v3 {
 		compatible = "regulator-fixed";
 		regulator-name = "VCC3V3";