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
replace inline assembly WebRtcAecm_ResetAdaptiveChannelNeon  by intrinsics.

The modification only uses the unique part of the ResetAdaptiveChannel
 function. Pass byte to byte conformance test both on ARM32 and ARM64,
 and the single function performance is similar with original assembly
 version on different platforms. If not specified, the code is compiled
 by GCC 4.6. The result is the "X version / C version" ratio, and the
 less is better.

| run 100k times             | cortex-a7 | cortex-a9 | cortex-a15 |
| use C as the base on each  |  (1.2Ghz) |  (1.0Ghz) |   (1.7Ghz) |
| CPU target                 |           |           |            |
|----------------------------+-----------+-----------+------------|
| Neon asm                   |       15% |       30% |        12% |
| Neon inline                |       21% |       30% |        12% |
| Neon intrinsics (GCC 4.6)  |       19% |       32% |        12% |
| Neon intrinsics (GCC 4.8)  |       20% |       32% |        12% |
| Neon intrinsics (LLVM 3.4) |       19% |       30% |        12% |

BUG=3580
R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/29019004

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

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7672 4adac7df-926f-26a2-2b94-8c16560cd09d