vboot_reference: fix several syntax warnings found by clang.

BUG=chromium:475949
TEST=CC=x86_64-cros-linux-gnu-clang CXX=x86_64-cros-linux-gnu-clang++
     emerge-falco vboot_reference
BRANCH=none
Change-Id: I3341e840c3f26f8579d35e0bb411566b0ad86164
Reviewed-on: https://chromium-review.googlesource.com/265834
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
3 files changed