test: fix problem with load android test cases

AVB verify_data structure must be initialized with zeros. This commit
also initialize secdata structure to avoid warning messages.

BUG=b:472612958
TEST="FEATURES=test  emerge-amd64-generic vboot_reference"
BRANCH=none

Change-Id: I3dde3d640534c9b4fea4c75329a5c66fb8540942
Signed-off-by: Grzegorz Bernacki <bernacki@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/7369392
Reviewed-by: Tomasz Michalec <tmichalec@google.com>