Realtek audio DMA engine

Required properties:
- compatible: Should be "realtek,<soctype>-adma"
	Examples with soctypes are:
	- "realtek,rts3903-adma" for RTS3903/RTS3904/RTS3913/RTS3914
	- "realtek,rts3915-adma" for RTS3915/RTS3916
- reg: physical base address of the audio dma engine and length of memory mapped
region
- memory-region: the audio reserved memory
- interrupt-parent: Phandle of the parent interrupt controller
- interrupts : Should contain the i2s interrupt number
- resets: List of phandle and reset specifier pairs, one pair for
each reset signal that affects the device
- reset-names: List of reset signal name strings sorted in the same order as
the resets property

Example:

	audio_dma: audio_dma@18500000 {
		compatible = "realtek,rts3903-adma";
		reg = <0x18500000 0x64 0x185000E4 0xc>;
		memory-region = <&audio_reserved>;
		interrupt-parent = <&vecintc>;
		interrupts = <BSP_IRQ_I2S>;
		resets = <&sysmem SYS_MEM_SD_AUDIO>;
		reset-names = "audio-sysmem-up";
		status = "disabled";
	};
