removed NetEq::EnableDtmf()

BUG=webrtc:1373
R=turaj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1822005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4492 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/neteq4/interface/neteq.h

@@ -164,9 +164,6 @@ class NetEq {
   // Not implemented.
   virtual int CurrentDelay() = 0;
 
-  // Enables playout of DTMF tones.
-  virtual int EnableDtmf() = 0;
-
   // Sets the playout mode to |mode|.
   virtual void SetPlayoutMode(NetEqPlayoutMode mode) = 0;