futility: Fix flash teardown issue

In setup_flash(), the control name is never stored in
cfg->prepare_ctrl_name, and therefore when teardown_flash() uses it to
restore the control, it will be a no-op.

BUG=b:283890697, b:288218235
TEST=sudo emerge vboot_reference
TEST=make runtests
TEST=sudo futility gbb --servo
BRANCH=none

Change-Id: Icaefdf577e3e0380c4d1b77325cfa270b72cd362
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/4648150
Reviewed-by: Yidi Lin <yidilin@chromium.org>
Commit-Queue: Yidi Lin <yidilin@chromium.org>
2 files changed