avcodec/hevc_ps: Fix c?_qp_offset_list size

Fixes: runtime error: index 5 out of bounds for type 'int8_t const[5]'
Fixes:3175/clusterfuzz-testcase-minimized-4736774054084608

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

libavcodec/hevc_ps.h

@@ -366,8 +366,8 @@ typedef struct HEVCPPS {
     uint8_t chroma_qp_offset_list_enabled_flag;
     uint8_t diff_cu_chroma_qp_offset_depth;
     uint8_t chroma_qp_offset_list_len_minus1;
-    int8_t  cb_qp_offset_list[5];
-    int8_t  cr_qp_offset_list[5];
+    int8_t  cb_qp_offset_list[6];
+    int8_t  cr_qp_offset_list[6];
     uint8_t log2_sao_offset_scale_luma;
     uint8_t log2_sao_offset_scale_chroma;