### What this PR does / why we need it?
This PR fixes a bug where the workspace of `_npu_paged_attention` in
setup is smaller than execution. For current implementation of
FULL_DECODE_ONLY with `_npu_paged_attention`, we use
`_npu_paged_attention_get_workspace` when capturing with `max_model_len`
as `seq_lens`. This assumes that PA with larger `seq_lens` inputs should
have larger workspace than smaller `seq_lens`. However, there are rare
cases where PA with smaller `seq_lens` incurs larger space. So I add
`get_workspace` directly into `update_attn_params`.
This change might introduce small(≈1%) performance degradation for low
num_tokens(such as 1) in decode phase, and there is no other known
memory issues. So I think this change is acceptable. We can remove this
if new attention op (such as `npu_fused_infer_attention_score`) does not
have such problems.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
- vLLM version: v0.11.0
- vLLM main:
83f478bb19
Signed-off-by: Angazenn <supperccell@163.com>
e0d58d543b