cpufreq: qcom-cpufreq: Add DT binding documentation

Qualcomm Technologies, Inc. CPUfreq device

msm-cpufreq is a device that represents the list of usable CPU frequencies

and provides a device handle for the CPUfreq driver to get the CPU and cache

clocks.

Required properties:

- compatible:		Must be "qcom,msm-cpufreq"

- qcom,cpufreq-table, or qcom,cpufreq-table-<X>:

			A list of usable CPU frequencies (KHz).

			Use "qcom,cpufreq-table" if all CPUs in the system

			should share same list of frequencies.

			Use "qcom,cpufreq-table-<cpuid>" to describe

			different CPU freq tables for different CPUs.

			The table should be listed only for the first CPU

			if multiple CPUs are synchronous.

Optional properties:

- clock-names:		When DT based binding of clock is available, this

			provides a list of CPU subsystem clocks.

			"cpuX_clk" for every CPU that's present.

			"l2_clk" when an async cache/CCI is present.

Optional properties:

- qcom,governor-per-policy:	This property denotes that governor tunables

				should be associated with each cpufreq policy

				group instead of being global.

Example:

	qcom,msm-cpufreq {

		compatible = "qcom,msm-cpufreq";

		qcom,cpufreq-table =

			<  300000 >,

			<  422400 >,

			<  652800 >,

			<  729600 >,

			<  883200 >,

			<  960000 >,

			< 1036800 >,

			< 1190400 >,

			< 1267200 >,

			< 1497600 >,

			< 1574400 >,

			< 1728000 >,

			< 1958400 >,

			< 2265600 >;

	};