* MTD SPI driver for serial flash chips

Required properties:
- #address-cells, #size-cells : Must be present if the device has sub-nodes
  representing partitions.
- compatible : Should be the manufacturer and the name of the chip. Bear in
               mind that the DT binding is not U-Boot-only, but in case of
               U-Boot, see spi_flash_params_table table in
               drivers/mtd/spi/sf_params.c for the list of supported chips.
- reg : Chip-Select number
- spi-max-frequency : Maximum frequency of the SPI bus the chip can operate at

Optional properties:
 - memory-map : Address and size of the flash, if memory mapped. This may
                apply to Intel chipsets, which tend to memory-map flash.

Example:

	flash: m25p80@0 {
		#address-cells = <1>;
		#size-cells = <1>;
		compatible = "spansion,m25p80";
		reg = <0>;
		spi-max-frequency = <40000000>;
	};