dt-bindings: add document of mediatek efuse driver

= Mediatek MTK-EFUSE device tree bindings =

This binding is intended to represent MTK-EFUSE which is found in most Mediatek SOCs.

Required properties:

- compatible: should be "mediatek,mt8173-efuse" or "mediatek,efuse"

- reg: Should contain registers location and length

= Data cells =

Are child nodes of MTK-EFUSE, bindings of which as described in

bindings/nvmem/nvmem.txt

Example:

	efuse: efuse@10206000 {

		compatible = "mediatek,mt8173-efuse";

		reg	   = <0 0x10206000 0 0x1000>;

		#address-cells = <1>;

		#size-cells = <1>;

		/* Data cells */

		thermal_calibration: calib@528 {

			reg = <0x528 0xc>;

		};

	};

= Data consumers =

Are device nodes which consume nvmem data cells.

For example:

	thermal {

		...

		nvmem-cells = <&thermal_calibration>;

		nvmem-cell-names = "calibration";

	};