dt-bindings: mtd: Document Macronix NAND device bindings

Macronix NANDs Device Tree Bindings

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Macronix NANDs support randomizer operation for scrambling user data,

which can be enabled with a SET_FEATURE. The penalty when using the

randomizer are subpage accesses prohibited and more time period needed

for program operation, i.e., tPROG 300us to 340us (randomizer enabled).

Enabling the randomizer is a one time persistent and non reversible

operation.

For more high-reliability concern, if subpage write is not available

with hardware ECC and not enabled at UBI level, then enabling the

randomizer is recommended by default by adding a new specific property

in children nodes.

Required NAND chip properties in children mode:

- randomizer enable: should be "mxic,enable-randomizer-otp"

Example:

	nand: nand-controller@unit-address {

		nand@0 {

			reg = <0>;

			mxic,enable-randomizer-otp;

		};

	};