ARM: dts: meson8b: ec100: 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/meson8b-ec100.dts

@@ -64,6 +64,11 @@ gpio-poweroff {
 		timeout-ms = <20000>;
 	};
 
+	iio-hwmon {
+		compatible = "iio-hwmon";
+		io-channels = <&saradc 8>;
+	};
+
 	leds {
 		compatible = "gpio-leds";