avformat/electronicarts: Check for EOF in each iteration of the loop in ea_read_packet()

Fixes: timeout(>20sec -> 1ms)
Fixes: 26526/clusterfuzz-testcase-minimized-ffmpeg_dem_EA_fuzzer-5672328069120000

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Peter Ross <pross@xvid.org>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 857aba7c45)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/electronicarts.c

@@ -582,6 +582,8 @@ static int ea_read_packet(AVFormatContext *s, AVPacket *pkt)
     int av_uninit(num_samples);
 
     while ((!packet_read && !hit_end) || partial_packet) {
+        if (avio_feof(pb))
+            return AVERROR_EOF;
         chunk_type = avio_rl32(pb);
         chunk_size = ea->big_endian ? avio_rb32(pb) : avio_rl32(pb);
         if (chunk_size < 8)