flashchips: Add Zettadevice ZD25D40

This introduces the Zettadevice manufacturer ID and adds support for the
ZD25D40 chip.

Based on PR20 from Github.
Change-Id: I0400b059ddacdf166d1b77f619becec3a250cece
Signed-off-by: David Hendricks <david.hendricks@gmail.com>
Reviewed-on: https://review.coreboot.org/23701
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
2 files changed