tests: initialize cmdline for AVB verify data BUG=b:399612484 TEST='USE_AVB=1 make runtests' BRANCH=main Change-Id: Ie494fe2db6ba553ceca5cb91b851d2fc36ee1736 Signed-off-by: Grzegorz Bernacki <[email protected]> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/7367473 Reviewed-by: Yu-Ping Wu <[email protected]> Commit-Queue: Yu-Ping Wu <[email protected]>