sched_ext: Optimize sched_ext_entity layout for cache locality

sched_ext: Optimize sched_ext_entity layout for cache locality

Reorder struct sched_ext_entity to place ops_state, ddsp_dsq_id, and
ddsp_enq_flags immediately after dsq. These fields are accessed together
in the do_enqueue_task() and finish_dispatch() hot paths but were
previously spread across three different cache lines. Grouping them on
the same cache line reduces cache misses on every enqueue and dispatch
operation.

Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>