ASoC: micfil: Add bindings for MICFIL DAI

NXP MICFIL Digital Audio Interface (MICFIL).

The MICFIL digital interface provides a 16-bit audio signal from a PDM

microphone bitstream in a configurable output sampling rate.

Required properties:

  - compatible		: Compatible list, contains "fsl,imx8mm-micfil"

  - reg			: Offset and length of the register set for the device.

  - interrupts		: Contains the micfil interrupts.

  - clocks		: Must contain an entry for each entry in clock-names.

  - clock-names		: Must include the "ipg_clk" for register access and

			  "ipg_clk_app" for internal micfil clock.

  - dmas		: Generic dma devicetree binding as described in

			  Documentation/devicetree/bindings/dma/dma.txt.

Example:

micfil: micfil@30080000 {

	compatible = "fsl,imx8mm-micfil";

	reg = <0x0 0x30080000 0x0 0x10000>;

	interrupts = <GIC_SPI 109 IRQ_TYPE_LEVEL_HIGH>,

		     <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;

	clocks = <&clk IMX8MM_CLK_PDM_IPG>,

		 <&clk IMX8MM_CLK_PDM_ROOT>;

	clock-names = "ipg_clk", "ipg_clk_app";

	dmas = <&sdma2 24 26 0x80000000>;

};