dt-bindings: arm64: allwinner: h6: Add binding for DMA controller

DMA in H6 is similar to other DMA controller, except it is first which
supports more than 32 request sources and has 16 channels. It also needs
additional clock to be enabled.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/sun6i-dma.txt

@@ -28,12 +28,17 @@ Example:
 	};
 
 ------------------------------------------------------------------------------
-For A64 DMA controller:
+For A64 and H6 DMA controller:
 
 Required properties:
-- compatible:	"allwinner,sun50i-a64-dma"
+- compatible:	Must be one of
+		  "allwinner,sun50i-a64-dma"
+		  "allwinner,sun50i-h6-dma"
 - dma-channels: Number of DMA channels supported by the controller.
 		Refer to Documentation/devicetree/bindings/dma/dma.txt
+- clocks:	In addition to parent AHB clock, it should also contain mbus
+		clock (H6 only)
+- clock-names:	Should contain "bus" and "mbus" (H6 only)
 - all properties above, i.e. reg, interrupts, clocks, resets and #dma-cells
 
 Optional properties: