NVIDIA nvpmodel driver bindings

Nvpmodel is a driver that provides sysfs nodes that allow capping certain clock
frequencies in order to keep the power consumption under a certain budget.

These caps are designed to be relatively static. They should not be used
during runtime (under load) to dynamically change the power budget.

Required properties:

- compatible: should be "nvidia,nvpmodel"

Optional properties:

- clocks: Clock IDs that the driver should support capping
- clock-names: List of strings which identify the relevant clocks

Both properties must have the same number of clocks. The strings that appear
in the clock-names property will be the names of the sysfs nodes that will be
provided. The clock IDs and names should appear in the same order.

Sample:

nvpmodel: {
        compatible = "nvidia,nvpmodel";
        clocks = <&tegra_car TEGRA186_CLK_NVENC
                        &tegra_car TEGRA186_CLK_NVDEC>;
        clock-names = "nvenc", "nvdec";
        status = "okay";
};