drivers/mtd_spi_nor: derive capacity from JEDEC ID
drivers/mtd_spi_nor: derive capacity from JEDEC ID

Most manufacturers (Spansion, Micron & ISSI) just encode the capacity
in the second ID byte.

Old Adesto (Atmel) chips use a different scheme here.

OlegHahm/RIOT,authmillenon/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,kaspar030/RIOT,jasonatran/RIOT,basilfx/RIOT,kaspar030/RIOT,ant9000/RIOT,jasonatran/RIOT,OTAkeys/RIOT,kYc0o/RIOT,ant9000/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,miri64/RIOT,OTAkeys/RIOT,authmillenon/RIOT,jasonatran/RIOT,miri64/RIOT,kYc0o/RIOT,kaspar030/RIOT,miri64/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,kaspar030/RIOT,kYc0o/RIOT,miri64/RIOT,basilfx/RIOT,miri64/RIOT,basilfx/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,ant9000/RIOT,kYc0o/RIOT,basilfx/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,authmillenon/RIOT,kYc0o/RIOT,ant9000/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,basilfx/RIOT,OTAkeys/RIOT,authmillenon/RIOT,ant9000/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,authmillenon/RIOT