rmdec: fix av_log level and context

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/rmdec.c

@@ -271,7 +271,7 @@ static int rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
         case DEINT_ID_VBRF:
             break;
         default:
-            av_log(NULL,0,"Unknown interleaver %X\n", ast->deint_id);
+            av_log(s, AV_LOG_ERROR, "Unknown interleaver %X\n", ast->deint_id);
             return AVERROR_INVALIDDATA;
         }