dt-bindings: iio: at91-sama5d2_adc: add optional dma property

Added property for DMA configuration of the device.
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt

@@ -17,6 +17,11 @@ Required properties:
   This property uses the IRQ edge types values: IRQ_TYPE_EDGE_RISING ,
   IRQ_TYPE_EDGE_FALLING or IRQ_TYPE_EDGE_BOTH
 
+Optional properties:
+  - dmas: Phandle to dma channel for the ADC.
+  - dma-names: Must be "rx" when dmas property is being used.
+  See ../../dma/dma.txt for details.
+
 Example:
 
 adc: adc@fc030000 {
@@ -31,4 +36,6 @@ adc: adc@fc030000 {
 	vddana-supply = <&vdd_3v3_lp_reg>;
 	vref-supply = <&vdd_3v3_lp_reg>;
 	atmel,trigger-edge-type = <IRQ_TYPE_EDGE_BOTH>;
+	dmas = <&dma0 (AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1) | AT91_XDMAC_DT_PERID(25))>;
+	dma-names = "rx";
 }