avcodec/jpeg2000dec: Skip init for component in CPRL if nothing is to be done

Fixes: assertion failure
Fixes: 7949/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-4819602782552064

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/jpeg2000dec.c

@@ -1159,6 +1159,9 @@ static int jpeg2000_decode_packets_po_iteration(Jpeg2000DecoderContext *s, Jpeg2
             step_x = 32;
             step_y = 32;
 
+            if (RSpoc > FFMIN(codsty->nreslevels, REpoc))
+                continue;
+
             for (reslevelno = RSpoc; reslevelno < FFMIN(codsty->nreslevels, REpoc); reslevelno++) {
                 uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                 Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;