Documentation: dma: sps: Add dt binding for SPS driver

SPS (Smart Peripheral Switch) may be used as a DMA engine to move data

in either the Peripheral-to-Peripheral (a.k.a. BAM-to-BAM) mode or the

Peripheral-to-Memory (a.k.a. BAM-System) mode. SPS includes BAM (Bus

Access Module) hardware block, BAM DMA peripheral, and pipe memory.

Required property:

  - compatible: should be "qcom,msm-sps" or "qcom,msm-sps-4k"

Optional properties:

  - reg: offset and size for the memory mapping, including maps for

    BAM DMA BAM, BAM DMA peripheral, pipe memory and reserved memory.

  - reg-names: indicates various resources passed to driver (via reg

    property) by name. "reg-names" examples are "bam_mem", "core_mem"

    , "pipe_mem" and "res_mem".

  - interrupts: IRQ line

  - qcom,device-type: specify the device configuration of BAM DMA and

    pipe memory. Can be one of

        1 - With BAM DMA and without pipe memory

        2 - With BAM DMA and with pipe memory

        3 - Without BAM DMA and without pipe memory

  - qcom,pipe-attr-ee: BAM pipes are attributed to a specific EE, with

    which we can know the pipes belong to apps side and can have the

    error interrupts at the pipe level.

  - clocks: This property shall provide a list of entries each of which

    contains a phandle to clock controller device and a macro that is

    the clock's name in hardware.These should be "clock_rpm" as clock

    controller phandle and "clk_pnoc_sps_clk" as macro for "dfab_clk"

    and "clock_gcc" as clock controller phandle and "clk_gcc_bam_dma_ahb_clk"

    as macro for "dma_bam_pclk".

  - clock-names: This property shall contain the clock input names used

    by driver in same order as the clocks property.These should be "dfab_clk"

    and "dma_bam_pclk".

Example:

	qcom,sps@f9980000 {

		compatible = "qcom,msm-sps";

		reg = <0xf9984000 0x15000>,

		      <0xf9999000 0xb000>,

		      <0xfe803000 0x4800>;

		interrupts = <0 94 0>;

		qcom,device-type = <2>;

		qcom,pipe-attr-ee;

		clocks = <&clock_rpm clk_pnoc_sps_clk>,

			 <&clock_gcc clk_gcc_bam_dma_ahb_clk>;

		clock-names = "dfab_clk", "dma_bam_pclk";

	};