* Generic OPP Interface

SoCs have a standard set of tuples consisting of frequency and
voltage pairs that the device will support per voltage domain. These
are called Operating Performance Points or OPPs.

Properties:
- operating-points: An array of 2-tuples items, and each item consists
  of frequency and voltage like <freq-kHz vol-uV>.
	freq: clock frequency in kHz
	vol: voltage in microvolt

Examples:

cpu@0 {
	compatible = "arm,cortex-a9";
	reg = <0>;
	next-level-cache = <&L2>;
	operating-points = <
		/* kHz    uV */
		792000  1100000
		396000  950000
		198000  850000
	>;
};
