Binding for Silicon Labs Si5324 programmable i2c clock generator.

Reference
[1] Si5324 Data Sheet
    http://www.silabs.com/Support%20Documents/TechnicalDocs/Si5324.pdf

The Si5324 is programmable i2c low-bandwidth, jitter-attenuating, precision
clock multiplier with up to 2 output clocks. The internal structure of the 
clock multiplier can be found in [1].

==I2C device node==

Required properties:
- compatible: shall be "silabs,si5324".
- reg: i2c device address, shall be 0x68.
- #clock-cells: from common clock binding; shall be set to 1.
- clocks: from common clock binding; list of parent clock
  handles, shall be xtal reference clock or xtal. Corresponding clock
  input names is "xtal"
- #address-cells: shall be set to 1.
- #size-cells: shall be set to 0.

==Child nodes==

Each of the clock outputs can be overwritten individually by
using a child node to the I2C device node. If a child node for a clock
output is not set, the eeprom configuration is not overwritten.

Required child node properties:
- reg: number of clock output.
- clock-frequency: default output frequency at power on

==Example==

	/* 114.285MHz reference crystal */
	refhdmi: refhdmi {
		compatible = "fixed-clock";
		#clock-cells = <0>;
		clock-frequency = <114285000>;
	};

	/* Si5324 i2c clock generator */
	si5324: clock-generator@68 {
		status = "okay";
		compatible = "silabs,si5324";
		reg = <0x68>;
		#address-cells = <1>;
		#size-cells = <0>;
		#clock-cells = <1>;
	
		/* input clock(s); the XTAL is hard-wired on the ZCU102 board */
		clocks = <&refhdmi>;
		clock-names = "xtal";
	
		/* output clocks */
		clk0 {
			reg = <0>;
			/* Reference clock output frequency */
			clock-frequency = <27000000>;
		};
	};
