Change in flashrom[master]: tests: Mock file i/o for linux_mtd and linux_spi tests

[Anastasia Klimchuk (Code Review)]

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

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

https://review.coreboot.org/c/flashrom/+/56413

to look at the new patch set (#10).

Change subject: tests: Mock file i/o for linux_mtd and linux_spi tests
......................................................................

tests: Mock file i/o for linux_mtd and linux_spi tests

This patch adds an init-shutdown test for linux_mtd. Since
linux_mtd is using file i/o operations, those are added to the
framework and mocked.

Another driver linux_spi which is also using file i/o, got an upgrade
in this patch, and it is now reading max buffer size from sysfs (using
mocked file i/o).

A good side-effect is that linux_mtd is the first test for opaque
masters, which is great to have in preparation for a change like
CB:56103 but for opaque masters.

BUG=b:181803212
TEST=builds and ninja test

Change-Id: I73f0d6ff2ad5074add7a721ed3416230d3647e3f
Signed-off-by: Anastasia Klimchuk 
---
M tests/init_shutdown.c
M tests/io_mock.h
M tests/meson.build
M tests/tests.c
M tests/tests.h
5 files changed, 180 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/13/56413/10