### What this PR does / why we need it? GDN Attention uses FIA's query_start_loc (padded), which may cause conv1d update errors under high concurrency when dp > 1, and this PR is to make GDN use its own query_start_loc (unpadded). ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? - vLLM version: v0.18.0 Signed-off-by: Wangbingjie <wangbj1207@126.com>