Vibra driver for the twl6040 family

The vibra driver is a child of the twl6040 MFD dirver.
Documentation/devicetree/bindings/mfd/twl6040.txt

Required properties:
- compatible : Must be "ti,twl6040-vibra";
- interrupts: 4, Vibra overcurrent interrupt
- vddvibl-supply: Regulator supplying the left vibra motor
- vddvibr-supply: Regulator supplying the right vibra motor
- vibldrv_res: Board specific left driver resistance
- vibrdrv_res: Board specific right driver resistance
- viblmotor_res: Board specific left motor resistance
- vibrmotor_res: Board specific right motor resistance

Optional properties:
- vddvibl_uV: If the vddvibl default voltage need to be changed
- vddvibr_uV: If the vddvibr default voltage need to be changed

Example:
/*
 * 8-channel high quality low-power audio codec
 * http://www.ti.com/lit/ds/symlink/twl6040.pdf
 */
twl6040: twl6040@4b {
	...
	twl6040_vibra: twl6040@1 {
		compatible = "ti,twl6040-vibra";
		interrupts = <4>;
		vddvibl-supply = <&vbat>;
		vddvibr-supply = <&vbat>;
		vibldrv_res = <8>;
		vibrdrv_res = <3>;
		viblmotor_res = <10>;
		vibrmotor_res = <10>;
	};
};