Device tree configuration for the I2C controller on the XLP9xx/5xx SoC

Required properties:
- compatible      : should be "netlogic,xlp980-i2c"
- reg             : bus address start and address range size of device
- interrupts      : interrupt number

Optional properties:
- clock-frequency : frequency of bus clock in Hz
                    Defaults to 100 KHz when the property is not specified

Example:

i2c0: i2c@113100 {
	compatible = "netlogic,xlp980-i2c";
	#address-cells = <1>;
	#size-cells = <0>;
	reg = <0 0x113100 0x100>;
	clock-frequency = <400000>;
	interrupts = <30>;
	interrupt-parent = <&pic>;
};