mtd: spi-nor: Add support for N25Q016A

This commit adds support in the spi-nor driver for the
N25Q016A, a 16Mbit SPI NOR flash from Micron.

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Jagan Teki <jteki@openedev.com>

Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>