UniPhier I2C controller (FIFO-less)

Required properties:
- compatible: should be "socionext,uniphier-i2c".
- #address-cells: should be 1.
- #size-cells: should be 0.
- reg: offset and length of the register set for the device.
- interrupts: a single interrupt specifier.
- clocks: phandle to the input clock.

Optional properties:
- clock-frequency: desired I2C bus frequency in Hz.  The maximum supported
  value is 400000.  Defaults to 100000 if not specified.

Examples:

	i2c0: i2c@58400000 {
		compatible = "socionext,uniphier-i2c";
		reg = <0x58400000 0x40>;
		#address-cells = <1>;
		#size-cells = <0>;
		interrupts = <0 41 1>;
		clocks = <&i2c_clk>;
		clock-frequency = <100000>;
	};