mtd: m25p80: Add support for Winbond W25Q80BW

Winbond W25Q80BW is a 8Mbit serial flash memory device.

Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>