dt-bindings: Add Tegra186 BPMP I2C binding

NVIDIA Tegra186 BPMP I2C controller

In Tegra186, the BPMP (Boot and Power Management Processor) owns certain HW

devices, such as the I2C controller for the power management I2C bus. Software

running on other CPUs must perform IPC to the BPMP in order to execute

transactions on that I2C bus. This binding describes an I2C bus that is

accessed in such a fashion.

The BPMP I2C node must be located directly inside the main BPMP node. See

../firmware/nvidia,tegra186-bpmp.txt for details of the BPMP binding.

This node represents an I2C controller. See ../i2c/i2c.txt for details of the

core I2C binding.

Required properties:

- compatible:

    Array of strings.

    One of:

    - "nvidia,tegra186-bpmp-i2c".

- #address-cells: Address cells for I2C device address.

    Single-cell integer.

    Must be <1>.

- #size-cells:

    Single-cell integer.

    Must be <0>.

- nvidia,bpmp-bus-id:

    Single-cell integer.

    Indicates the I2C bus number this DT node represent, as defined by the

    BPMP firmware.

Example:

bpmp {

	...

	i2c {

		compatible = "nvidia,tegra186-bpmp-i2c";

		#address-cells = <1>;

		#size-cells = <0>;

		nvidia,bpmp-bus-id = <5>;

	};

};