* Realtek DMA Controller

Required properties:
- compatible: "realtek,rts3903-dmac"
- reg: Address range of the DMAC registers
- interrupt: Should contain the DMAC interrupt number
- clocks: Clock for dma controller
- dma-channels: Number of channels supported by hardware
- dma-vchannels: Number of virtual channels
- dma-masters: Number of AHB masters supported by the controller
- chan_priority: priority of channels. 0 (default): increase from chan 0->n, 1:
  increase from chan n->0
- block_size: Maximum block size supported by the controller
- data-width: Maximum data width supported by hardware per AHB master
  (in bytes, power of 2)

Optional properties:
- interrupt-parent: Should be the phandle for the interrupt controller
  that services interrupts for this device
- is_private: The device channels should be marked as private and not for by the
  general purpose DMA channel allocator. False if not passed.

Example:

	dmahost: dma@18020000 {
		compatible = "realtek,rts3903-dmac";
		reg = <0x18020000 0x100>;
		interrupt-parent = <&cpuintc>;
		interrupts = <BSP_IRQ_DMA>;

		dma-channels = <4>;
		dma-requests = <4>;
		dma-masters = <1>;
		chan_priority = <1>;
		block_size = <0xfff>;
		data-width = <2 2 0 0>;
	};
