common_audio/vad: Removes head allocation failure check

Related to https://webrtc-codereview.appspot.com/51919004/ where Create() was changed. This CL removes a useless malloc failure check.

BUG=441, 3347
R=kwiberg@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/51109004

Cr-Commit-Position: refs/heads/master@{#9312}
2 files changed