[audio_core] Clang-tidy fixes

This CL addresses the clang-analyzer-security, clang-analyzer-core,
clang-analyzer-optin.cplusplus and clang-analyzer-deadcode warnings
generated by git-file-tidy --all and represented in MTWN-219.

Test: Build, CQ, "git-file-tidy --all" from audio_core dir

MTWN-219 #done

Change-Id: I40a75b2924cab98193b8d64ab80f60a2b4f3c978
6 files changed