CRAS: fmt_conv_ops_unittest - Fix invalid memory access

BUG=chromium:921644
TEST=USE=asan FEATURES=test emerge-octopus adhd

Change-Id: I169e266f0758d4389e1807ffa418f39271acbfc4
Reviewed-on: https://chromium-review.googlesource.com/1410403
Commit-Ready: Hsinyu Chao <hychao@chromium.org>
Tested-by: Hsinyu Chao <hychao@chromium.org>
Reviewed-by: Tzung-Bi Shih <tzungbi@chromium.org>
1 file changed