avformat/flacdec: Avoid double AVERRORS

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/flacdec.c

@@ -78,7 +78,7 @@ static int flac_read_header(AVFormatContext *s)
     /* process metadata blocks */
     while (!avio_feof(s->pb) && !metadata_last) {
         if (avio_read(s->pb, header, 4) != 4)
-            return AVERROR(AVERROR_INVALIDDATA);
+            return AVERROR_INVALIDDATA;
         flac_parse_block_header(header, &metadata_last, &metadata_type,
                                    &metadata_size);
         switch (metadata_type) {