* NXP LPC32xx SoC ADC controller

Required properties:
- compatible: must be "nxp,lpc3220-adc"
- reg: physical base address of the controller and length of memory mapped
  region.
- interrupts: The ADC interrupt

Optional:
 - vref-supply: The regulator supply ADC reference voltage, optional
   for legacy reason, but highly encouraging to us in new device tree

Example:

	adc@40048000 {
		compatible = "nxp,lpc3220-adc";
		reg = <0x40048000 0x1000>;
		interrupt-parent = <&mic>;
		interrupts = <39 0>;
		vref-supply = <&vcc>;
	};
