flashrom_tester: Simplify WriteProtectState

Remove the WriteProtectState 'stack' implementation and the push
function. This functionality allowed states to be stacked and then
automatically unrolled via RAII lifetimes. This was useful. However this
unrolling could make errors in a flashrom_tester run much harder to
understand, as the actual failure would be followed by multiple write
protect calls that could subsequently fail, potentially causing panicing
inside the panic handler and the process to be hard aborted and the
restore golden image function would not be run.

The new approach is to prefer code simplicity. Ideally this makes errors
easier to diagnose from logs. To that end the lifetime has been
simplified. The stack has been removed. The mutex has been removed.
This means tests may not be running in the same environment they were
previously. However if they continue to specify their requirements with
set_sw and set_hw there will be no difference and the errors will be
clear.

BUG=b:259494812
BRANCH=None
TEST=flashrom_tester --libflashrom host

Change-Id: I1c4251f69b42a327383b8a99fa933f411feb9568
Signed-off-by: Evan Benn <evanbenn@chromium.org>
---
M util/flashrom_tester/src/tester.rs
1 file changed, 68 insertions(+), 187 deletions(-)