dt-bindings: arm: Hi6220: add doc for SRAM controller

		#clock-cells = <1>;

	};

Hisilicon Hi6220 SRAM controller

Required properties:

- compatible : "hisilicon,hi6220-sramctrl", "syscon"

- reg : Register address and size

Hisilicon's SoCs use sram for multiple purpose; on Hi6220 there have several

SRAM banks for power management, modem, security, etc. Further, use "syscon"

managing the common sram which can be shared by multiple modules.

Example:

	/*for Hi6220*/

	sram: sram@fff80000 {

		compatible = "hisilicon,hi6220-sramctrl", "syscon";

		reg = <0x0 0xfff80000 0x0 0x12000>;

	};

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Hisilicon HiP01 system controller