Freescale vf610 Digital to Analog Converter bindings

The devicetree bindings are for the new DAC driver written for
vf610 SoCs from Freescale.

Required properties:
- compatible: Should contain "fsl,vf610-dac"
- reg: Offset and length of the register set for the device
- interrupts: Should contain the interrupt for the device
- clocks: The clock is needed by the DAC controller
- clock-names: Must contain "dac" matching entry in the clocks property.

Example:
dac0: dac@400cc000 {
	compatible = "fsl,vf610-dac";
	reg = <0x400cc000 0x1000>;
	interrupts = <55 IRQ_TYPE_LEVEL_HIGH>;
	clock-names = "dac";
	clocks = <&clks VF610_CLK_DAC0>;
};