mtd: spi-nor: Add support for ESMT F25L32QA and F25L64QA

Add support for the ESMT F25L32QA and F25L64QA.
These are 4MB and 8MB SPI-NOR Chips from Elite Semiconductor Memory
Technology.

Signed-off-by: L. D. Pinney <ldpinney@gmail.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>