dt-bindings: devfreq: Add documentation for static map governor

MSM Static Map governor

static map governor is a device that registers with a clock notifier

of the master port and votes for the slave port using the core-dev freq

mapping table. The idea behind the governor is to match the voltage corners

of the master and slave ports when voting for the bandwidth.

Required properties:

- compatible:		Must be "qcom,static-map"

- clocks:		The phandles for clock specified in "clock-names" property

- clock-names:		Names of the clocks for registering a notifier

- qcom,dev-clk:		Names of the clocks for registering a notifier

- qcom,target-dev:	The DT device that corresponds to this master port

- qcom,core-dev-table:		A mapping table of core frequency to a required

				bandwidth vote at the given core frequency.

Example:

	npu_staticmap_mon: qcom,npu-staticmap-mon {

		compatible = "qcom,static-map";

		qcom,target-dev = <&npu_ddr_static>;

		clocks = <&clock_npucc NPU_CC_CAL_HM0_CLK>;

		clock-names = "cal_hm0_clk";

		qcom,dev_clk = "cal_hm0_clk";

		qcom,core-dev-table =

				<       0 MHZ_TO_MBPS(    0, 4) >,

				<  200000 MHZ_TO_MBPS(  451, 4) >,

				<  466000 MHZ_TO_MBPS(  768, 4) >,

				<  533000 MHZ_TO_MBPS( 1017, 4) >,

				<  850000 MHZ_TO_MBPS( 1555, 4) >,

				< 1000000 MHZ_TO_MBPS( 2736, 4) >;

	};