Change in flashrom[master]: spi25_statusreg,flashchips: add SR2 read/write support

[Nikolai Artemiev (Code Review)]

Attention is currently required from: Angel Pons, Nikolai Artemiev, Sergii Dmytruk.
Hello build bot (Jenkins), Nico Huber, Edward O'Callaghan, Angel Pons, Anastasia Klimchuk, Sergii Dmytruk,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/flashrom/+/58570

to look at the new patch set (#27).

Change subject: spi25_statusreg,flashchips: add SR2 read/write support
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spi25_statusreg,flashchips: add SR2 read/write support

This patch adds support for reading and writing the second status
register and enables it on a limited set of flash chips.

Chip support for RDSR2/WRSR2/extended WRSR is represented using feature
flags to be consistent with how other SPI capabilities are represented.

BUG=b:195381327,b:153800563
BRANCH=none
TEST=flashrom -{r,w,E}
TEST=flashrom --wp-{enable,disable,range,list,status} at end of patch series
TEST=logged SR2 read/write values during wp commands

Change-Id: I34a503b0958e8f2f22a2a993a6ea529eb46b41db
Signed-off-by: Nikolai Artemiev 
---
M flash.h
M flashchips.c
M spi.h
M spi25_statusreg.c
4 files changed, 53 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/70/58570/27