- Move temporary sglists into the session structure and protect them with a per-session lock instead of a per-adapter lock.
- Retire an unused session field, and move a debugging field under INVARIANTS to avoid using the session lock for completion handling when INVARIANTS isn't enabled.
- Use counter_u64 for per-adapter statistics.
Note that this helps for cases where multiple sessions are used
(e.g. multiple IPsec SAs or multiple KTLS connections). It does not
help for workloads that use a single session (e.g. a single GELI