Add a SPI command class to `struct flashchip`

By default, we want to probe for SPI25 chips only. Other SPI use cases,
like the ENE/EDI protocol, might use commands that can confuse these
common chips.

Now, flashrom will probe for a chip only if one of these conditions is
true:
1) no chip has been specified AND the chip uses the SPI25 commands
2) this chip has been specified by -c | --chip <chipname>

Change-Id: I89a53ccaef2791a2ac32904d7ab813da7478a6f0
Signed-off-by: Mike Banon <mikebdp2@gmail.com>
Signed-off-by: Nico Huber <nico.h@gmx.de>
Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
---
M flash.h
M flashrom.c
2 files changed, 14 insertions(+), 0 deletions(-)