ARM: dts: at91: sama5d2: add channel cells for ADC device

Preparing the ADC device to connect channel consumer drivers
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

arch/arm/boot/dts/sama5d2.dtsi

@@ -47,6 +47,7 @@
 #include <dt-bindings/dma/at91.h>
 #include <dt-bindings/interrupt-controller/irq.h>
 #include <dt-bindings/clock/at91.h>
+#include <dt-bindings/iio/adc/at91-sama5d2_adc.h>
 
 / {
 	model = "Atmel SAMA5D2 family SoC";
@@ -1437,6 +1438,7 @@ adc: adc@fc030000 {
 				atmel,max-sample-rate-hz = <20000000>;
 				atmel,startup-time-ms = <4>;
 				atmel,trigger-edge-type = <IRQ_TYPE_EDGE_RISING>;
+				#io-channel-cells = <1>;
 				status = "disabled";
 			};