Documentation: DT: Add binding documentation for NVIDIA ADMA

Add device-tree binding documentation for the Tegra210 Audio DMA
controller.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Documentation/devicetree/bindings/dma/nvidia,tegra210-adma.txt

+* NVIDIA Tegra Audio DMA (ADMA) controller
+
+The Tegra Audio DMA controller that is used for transferring data
+between system memory and the Audio Processing Engine (APE).
+
+Required properties:
+- compatible: Must be "nvidia,tegra210-adma".
+- reg: Should contain DMA registers location and length. This should be
+  a single entry that includes all of the per-channel registers in one
+  contiguous bank.
+- interrupt-parent: Phandle to the interrupt parent controller.
+- interrupts: Should contain all of the per-channel DMA interrupts in
+  ascending order with respect to the DMA channel index.
+- clocks: Must contain one entry for the ADMA module clock
+  (TEGRA210_CLK_D_AUDIO).
+- clock-names: Must contain the name "d_audio" for the corresponding
+  'clocks' entry.
+- #dma-cells : Must be 1. The first cell denotes the receive/transmit
+  request number and should be between 1 and the maximum number of
+  requests supported. This value corresponds to the RX/TX_REQUEST_SELECT
+  fields in the ADMA_CHn_CTRL register.
+
+
+Example:
+
+adma: dma@702e2000 {
+	compatible = "nvidia,tegra210-adma";
+	reg = <0x0 0x702e2000 0x0 0x2000>;
+	interrupt-parent = <&tegra_agic>;
+	interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 25 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 27 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 28 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 29 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 30 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 33 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 35 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 36 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 38 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 39 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 41 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 42 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 43 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>,
+		     <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH>;
+	clocks = <&tegra_car TEGRA210_CLK_D_AUDIO>;
+	clock-names = "d_audio";
+	#dma-cells = <1>;
+};