* Atmel Direct Memory Access Controller (DMA)

Required properties:
- compatible: Should be "atmel,<chip>-dma".
- reg: Should contain DMA registers location and length.
- interrupts: Should contain DMA interrupt.
- #dma-cells: Must be <2>, used to represent the number of integer cells in
the dmas property of client devices.

Example:

dma0: dma@ffffec00 {
	compatible = "atmel,at91sam9g45-dma";
	reg = <0xffffec00 0x200>;
	interrupts = <21>;
	#dma-cells = <2>;
};

DMA clients connected to the Atmel DMA controller must use the format
described in the dma.txt file, using a three-cell specifier for each channel:
a phandle plus two integer cells.
The three cells in order are:

1. A phandle pointing to the DMA controller.
2. The memory interface (16 most significant bits), the peripheral interface
(16 less significant bits).
3. Parameters for the at91 DMA configuration register which are device
dependent:
  - bit 7-0: peripheral identifier for the hardware handshaking interface. The
  identifier can be different for tx and rx.
  - bit 11-8: FIFO configuration. 0 for half FIFO, 1 for ALAP, 2 for ASAP.

Example:

i2c0@i2c@f8010000 {
	compatible = "atmel,at91sam9x5-i2c";
	reg = <0xf8010000 0x100>;
	interrupts = <9 4 6>;
	dmas = <&dma0 1 7>,
	       <&dma0 1 8>;
	dma-names = "tx", "rx";
};