remove no more needed field

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@12968 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/adpcm.c

@@ -148,7 +148,6 @@ typedef struct ADPCMChannelStatus {
 } ADPCMChannelStatus;
 
 typedef struct ADPCMContext {
-    int channel; /* for stereo MOVs, decode left, then decode right, then tell it's decoded */
     ADPCMChannelStatus status[6];
 } ADPCMContext;