NVIDIA I2C controller driver interface.

Required properties:
- compatible : The driver is compatible with
	"nvidia,tegra114-i2c".
	"nvidia,tegra30-i2c".
	"nvidia,tegra20-i2c",
	"nvidia,tegra20-i2c-dvc".
- reg: Should contain I2C registers location and length.
- interrupts: Should contain I2C interrupts.
- nvidia,dma-request-selector : The Tegra DMA controller's phandle and
  request selector for this SLINK controller.

Recommended properties:
- clock-frequency: desired I2C bus clock frequency in Hz.

Optional properties:
- nvidia,clock-always-on: If clock should be always ON and dynamic clock management
	need to be disable.
- nvidia,hs-master-code: Hisgh speed master code if highspeed mode need to be enable.

Example:

	i2c@7000c000 {
		compatible =  "nvidia,tegra30-i2c", "nvidia,tegra20-i2c";
		reg = <0x7000c000 0x100>;
		interrupts = <0 38 0x04>;
		clock-frequency = <100000>;
		nvidia,clock-always-on;
		nvidia,hs-master-code = <0x1234>;
		#address-cells = <1>;
		#size-cells = <0>;
		status = "disabled";
	}; 

