The number of channels must be set correctly before calling ProcessStream. This
was preventing stereo frames from being processed.
Also fix voe_cmd_test, which wasn't enabling rx NS properly.
BUG=issue713, 7375579
Review URL: https://webrtc-codereview.appspot.com/929013
git-svn-id: http://webrtc.googlecode.com/svn/trunk@3047 4adac7df-926f-26a2-2b94-8c16560cd09d