clear asm code and unused functions in audio processing module

BUG=
R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/25119004

Patch from Zhongwei Yao <zhongwei.yao@arm.com>.

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7671 4adac7df-926f-26a2-2b94-8c16560cd09d