ASoC: omap-dmic: Add device tree bindings

Device tree support for OMAP4+ dmic cpu dai driver.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@ti.com>

Documentation/devicetree/bindings/sound/omap-dmic.txt

@@ -0,0 +1,21 @@
+* Texas Instruments OMAP4+ Digital Microphone Module
+
+Required properties:
+- compatible: "ti,omap4-dmic"
+- reg: Register location and size as an array:
+       <MPU access base address, size>,
+       <L3 interconnect address, size>;
+- interrupts: Interrupt number for DMIC
+- interrupt-parent: The parent interrupt controller
+- ti,hwmods: Name of the hwmod associated with OMAP dmic IP
+
+Example:
+
+dmic: dmic@4012e000 {
+	compatible = "ti,omap4-dmic";
+	reg = <0x4012e000 0x7f>, /* MPU private access */
+	      <0x4902e000 0x7f>; /* L3 Interconnect */
+	interrupts = <0 114 0x4>;
+	interrupt-parent = <&gic>;
+	ti,hwmods = "dmic";
+};