vboot: fix vb2_gbb_read_recovery_key to save into int

Return value of vb2_gbb_read_recovery_key should be saved into an
integer, not into vboot1-style VbError_t.

BUG=b:124141368, chromium:954774
TEST=make clean && make runtests
BRANCH=none

Change-Id: Icbe622c9958d3f303da0faf7b52b0ce52c2b16a5
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1648093
Tested-by: Joel Kitching <kitching@chromium.org>
Auto-Submit: Joel Kitching <kitching@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Commit-Queue: Julius Werner <jwerner@chromium.org>
2 files changed