* I2C controller embedded in STMicroelectronics STM32 I2C platform

Required properties :
- compatible : Must be "st,stm32f4-i2c"
- reg : Offset and length of the register set for the device
- interrupts : Must contain the interrupt id for I2C event and then the
  interrupt id for I2C error.
- resets: Must contain the phandle to the reset controller.
- clocks: Must contain the input clock of the I2C instance.
- A pinctrl state named "default" must be defined to set pins in mode of
  operation for I2C transfer
- #address-cells = <1>;
- #size-cells = <0>;

Optional properties :
- clock-frequency : Desired I2C bus clock frequency in Hz. If not specified,
  the default 100 kHz frequency will be used. As only Normal and Fast modes
  are supported, possible values are 100000 and 400000.

Example :

	i2c@40005400 {
		compatible = "st,stm32f4-i2c";
		#address-cells = <1>;
		#size-cells = <0>;
		reg = <0x40005400 0x400>;
		interrupts = <31>,
			     <32>;
		resets = <&rcc 277>;
		clocks = <&rcc 0 149>;
		pinctrl-0 = <&i2c1_sda_pin>, <&i2c1_scl_pin>;
		pinctrl-names = "default";
	};
