adhd: Fix undefined behavior in cras_fmt_conv and its unittest

Shifting negative integer is an undefined behavior. We need to cast them
to unsigned integer explicitly before we use left shift.

BUG=chromium:857597
TEST=FEATURE=test USE=asan emerge-amd64-generic adhd

Change-Id: I641885ecd353fd3852de25ba271bc2419e1aac21
Reviewed-on: https://chromium-review.googlesource.com/1127504
Commit-Ready: Chih-Yang Hsia <paulhsia@chromium.org>
Tested-by: Chih-Yang Hsia <paulhsia@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>
2 files changed