[audio-core] ASAN fix (buffer overrun)

This CL addresses the ASAN issues raised in MTWN-212.

Test: Build, CQ, "git-file-tidy --all" from audio_core dir,
ASAN build that confirms the defect is addressed.

MTWN-212 #done

Change-Id: Ied0ed63be0770a16752ef0a9bc97c2532d7a23ac
1 file changed