avcodec/cbs_h266_syntax_template: Check tile_y

Fixes: out of array access
Fixes: 67021/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-4883576579489792

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

libavcodec/cbs_h266_syntax_template.c

@@ -2072,6 +2072,8 @@ static int FUNC(pps) (CodedBitstreamContext *ctx, RWContext *rw,
 
                 tile_x = tile_idx % current->num_tile_columns;
                 tile_y = tile_idx / current->num_tile_columns;
+                if (tile_y >= current->num_tile_rows)
+                    return AVERROR_INVALIDDATA;
 
                 ctu_x = 0, ctu_y = 0;
                 for (j = 0; j < tile_x; j++) {