ASoC: cygnus: Add DT bindings for Broadcom Cygnus audio

BROADCOM Cygnus Audio I2S/TDM/SPDIF controller

Required properties:

	- compatible : "brcm,cygnus-audio"

	- #address-cells: 32bit valued, 1 cell.

	- #size-cells:  32bit valued, 0 cell.

	- reg : Should contain audio registers location and length

	- reg-names: names of the registers listed in "reg" property

		Valid names are "aud" and "i2s_in". "aud" contains a

		set of DMA, I2S_OUT and SPDIF registers. "i2s_in" contains

		a set of I2S_IN registers.

	- clocks: PLL and leaf clocks used by audio ports

	- assigned-clocks: PLL and leaf clocks

	- assigned-clock-parents: parent clocks of the assigned clocks

		(usually the PLL)

	- assigned-clock-rates: List of clock frequencies of the

		assigned clocks

	- clock-names: names of 3 leaf clocks used by audio ports

		Valid names are "ch0_audio", "ch1_audio", "ch2_audio"

	- interrupts: audio DMA interrupt number

SSP Subnode properties:

- reg: The index of ssp port interface to use

	Valid value are 0, 1, 2, or 3 (for spdif)

Example:

	cygnus_audio: audio@180ae000 {

		compatible = "brcm,cygnus-audio";

		#address-cells = <1>;

		#size-cells = <0>;

		reg = <0x180ae000 0xafd>, <0x180aec00 0x1f8>;

		reg-names = "aud", "i2s_in";

		clocks = <&audiopll BCM_CYGNUS_AUDIOPLL_CH0>,

				<&audiopll BCM_CYGNUS_AUDIOPLL_CH1>,

				<&audiopll BCM_CYGNUS_AUDIOPLL_CH2>;

		assigned-clocks = <&audiopll BCM_CYGNUS_AUDIOPLL>,

							<&audiopll BCM_CYGNUS_AUDIOPLL_CH0>,

							<&audiopll BCM_CYGNUS_AUDIOPLL_CH1>,

							<&audiopll BCM_CYGNUS_AUDIOPLL_CH2>;

		assigned-clock-parents = <&audiopll BCM_CYGNUS_AUDIOPLL>;

		assigned-clock-rates = <1769470191>,

								<0>,

								<0>,

								<0>;

		clock-names = "ch0_audio", "ch1_audio", "ch2_audio";

		interrupts = <GIC_SPI 143 IRQ_TYPE_LEVEL_HIGH>;

		ssp0: ssp_port@0 {

			reg = <0>;

			status = "okay";

		};

		ssp1: ssp_port@1 {

			reg = <1>;

			status = "disabled";

		};

		ssp2: ssp_port@2 {

			reg = <2>;

			status = "disabled";

		};

		spdif: spdif_port@3 {

			reg = <3>;

			status = "disabled";

		};

	};