Add support for Atmel / Adesto AT25SF041 SPI flash chip

Reasonably certain this is working due to erase/read/write hardware-tests in a setup in which the flash content contained a running FPGA program. Meaningful content was stored on the chip beforehand. I read a.rom, erased, observed the FPGA dead, read b.rom, wrote back a.rom, observed the FPGA alive again. I verified b.rom in a hex editor contained 0xff only.
The FPGA data used only a small portion of the address space, so I also wrote out a file with specific 3 bytes in the first and last memory page. All flashrom verify cycles passed.

Change-Id: I0be930ff2258300508398e12fbe5abe10400fea2
Signed-off-by: Julian von Mendel <git@jinvent.de>
Signed-off-by: jvm <git@jinvent.de>
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M flashchips.c
M flashchips.h
2 files changed, 33 insertions(+), 0 deletions(-)