avcodec/hevc_ps: Fix runtime error: index 32 out of bounds for type 'uint8_t [32]'

Fixes: 2010/clusterfuzz-testcase-minimized-6209288450080768

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