vboot: Add const modifier to vb2api_relocate argument

BRANCH=none
BUG=none
TEST=emerge-nami vboot_reference coreboot

Change-Id: I83a82a8b931c074e83ced8ea41c215d70825881e
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1935272
Reviewed-by: Joel Kitching <kitching@chromium.org>
2 files changed