vaapi: h265dec: Refresh our sps/pps copy
The decoder uses a copy of the SPS/PPS. Since !2575 (merged) the SPS/PPS is updated when the slice header is parsed. As a side effect, the H265 decoder was using an partially filled copy.
Fixes: 5ae05bb4 ("codecparsers: Defering computation of pps and sps fields")
Fixes: #1343 (closed)