set sample rate in more logical place, kill warning

Originally committed as revision 9552 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpegaudio_parser.c

@@ -146,10 +146,10 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
                         s->frame_size = -1;
                     }
 #endif
-                }
                 if(s->header_count > 1)
                     avctx->sample_rate= sr;
                 }
+            }
         } else
 #if 0
         if (s->frame_size == -1) {