NVIDIA Tegra MIPI pad calibration controller

Required properties:
- compatible: "nvidia,tegra<chip>-mipi"
- reg: Physical base address and length of the controller's registers.
- clocks: The clock consumed by the controller.
- #calibrate-cells: Should be 1. The cell is a bitmask of the pads that need
  to be calibrated by a given device.

User nodes need to contain a calibrate property that has a phandle to refer
to the calibration controller node and a bitmask of the pads that need to be
calibrated.

Example:

	mipi: mipi@700e3000 {
		compatible = "nvidia,tegra114-mipi";
		reg = <0x700e3000 0x100>;
		clocks = <&tegra_car TEGRA114_CLK_MIPI_CAL>;
		#calibrate-cells = <1>;
	};

	...

	host1x@50000000 {
		...

		dsi@54300000 {
			...

			calibrate = <&mipi 0x060>;

			...
		};

		...
	};