i2c: qup: Add device tree bindings information

Qualcomm Universal Peripheral (QUP) I2C controller

Required properties:

 - compatible: Should be:

   * "qcom,i2c-qup-v1.1.1" for 8660, 8960 and 8064.

   * "qcom,i2c-qup-v2.1.1" for 8974 v1.

   * "qcom,i2c-qup-v2.2.1" for 8974 v2 and later.

 - reg: Should contain QUP register address and length.

 - interrupts: Should contain I2C interrupt.

 - clocks: A list of phandles + clock-specifiers, one for each entry in

   clock-names.

 - clock-names: Should contain:

   * "core" for the core clock

   * "iface" for the AHB clock

 - #address-cells: Should be <1> Address cells for i2c device address

 - #size-cells: Should be <0> as i2c addresses have no size component

Optional properties:

 - clock-frequency: Should specify the desired i2c bus clock frequency in Hz,

                    defaults to 100kHz if omitted.

Child nodes should conform to i2c bus binding.

Example:

 i2c@f9924000 {

 	compatible = "qcom,i2c-qup-v2.2.1";

 	reg = <0xf9924000 0x1000>;

 	interrupts = <0 96 0>;

 	clocks = <&gcc GCC_BLSP1_QUP2_I2C_APPS_CLK>, <&gcc GCC_BLSP1_AHB_CLK>;

 	clock-names = "core", "iface";

 	clock-frequency = <355000>;

 	#address-cells = <1>;

 	#size-cells = <0>;

 };