TPS65217 family of regulators

The TPS65217 chip contains a boost converter and current sinks which can be
used to drive LEDs for use as backlights.

Required properties:
- compatible: "ti,tps65217"
- reg: I2C slave address
- backlight: node for specifying WLED1 and WLED2 lines in TPS65217
- isel: selection bit, valid values: 1 for ISEL1 (low-level) and 2 for ISEL2 (high-level)
- fdim: PWM dimming frequency, valid values: 100, 200, 500, 1000
- default-brightness: valid values: 0-100

Each regulator is defined using the standard binding for regulators.

Example:

	tps: tps@24 {
		reg = <0x24>;
		compatible = "ti,tps65217";
		backlight {
			isel = <1>;  /* 1 - ISET1, 2 ISET2 */
			fdim = <100>; /* TPS65217_BL_FDIM_100HZ */
			default-brightness = <50>;
		};
	};

