vboot: replace VBERROR_UNKNOWN with VB2_ERROR_UNKNOWN

Replace vboot1-style VBERROR_UNKNOWN with VB2_ERROR_UNKNOWN.

BUG=b:124141368, chromium:988410
TEST=make clean && make runtests
BRANCH=none

Change-Id: Icd2158e328142cff69ce94b5396ab021a1f7839c
Signed-off-by: Joel Kitching <kitching@google.com>
Cq-Depend: chromium:1728115
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1722916
Commit-Queue: Joel Kitching <kitching@chromium.org>
Tested-by: Joel Kitching <kitching@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
12 files changed