dmaengine: qcom_bam_dma: Add device tree binding

QCOM BAM DMA controller

Required properties:

- compatible: must contain "qcom,bam-v1.4.0" for MSM8974

- reg: Address range for DMA registers

- interrupts: Should contain the one interrupt shared by all channels

- #dma-cells: must be <1>, the cell in the dmas property of the client device

  represents the channel number

- clocks: required clock

- clock-names: must contain "bam_clk" entry

- qcom,ee : indicates the active Execution Environment identifier (0-7) used in

  the secure world.

Example:

	uart-bam: dma@f9984000 = {

		compatible = "qcom,bam-v1.4.0";

		reg = <0xf9984000 0x15000>;

		interrupts = <0 94 0>;

		clocks = <&gcc GCC_BAM_DMA_AHB_CLK>;

		clock-names = "bam_clk";

		#dma-cells = <1>;

		qcom,ee = <0>;

	};

DMA clients must use the format described in the dma.txt file, using a two cell

specifier for each channel.

Example:

	serial@f991e000 {

		compatible = "qcom,msm-uart";

		reg = <0xf991e000 0x1000>

			<0xf9944000 0x19000>;

		interrupts = <0 108 0>;

		clocks = <&gcc GCC_BLSP1_UART2_APPS_CLK>,

			<&gcc GCC_BLSP1_AHB_CLK>;

		clock-names = "core", "iface";

		dmas = <&uart-bam 0>, <&uart-bam 1>;

		dma-names = "rx", "tx";

	};