EEPROMs (SPI) compatible with Microchip Technology 93xx46 family.

Required properties:
- compatible : shall be one of:
    "atmel,at93c46d"
    "eeprom-93xx46"
- data-size : number of data bits per word (either 8 or 16)

Optional properties:
- read-only : parameter-less property which disables writes to the EEPROM
- select-gpios : if present, specifies the GPIO that will be asserted prior to
  each access to the EEPROM (e.g. for SPI bus multiplexing)

Property rules described in Documentation/devicetree/bindings/spi/spi-bus.txt
apply.  In particular, "reg" and "spi-max-frequency" properties must be given.

Example:
	eeprom@0 {
		compatible = "eeprom-93xx46";
		reg = <0>;
		spi-max-frequency = <1000000>;
		spi-cs-high;
		data-size = <8>;
		select-gpios = <&gpio4 4 GPIO_ACTIVE_HIGH>;
	};
