net/sched: sch_cake: annotate data-races in cake_dump_class_stats (II)

cake_dump_class_stats() runs without qdisc spinlock being held.

In this second patch, I add READ_ONCE()/WRITE_ONCE() annotations for:

- flow->deficit
- flow->cvars.dropping
- flow->cvars.count
- flow->cvars.p_drop
- flow->cvars.blue_timer
- flow->cvars.drop_next

Fixes: 046f6fd5daef ("sched: Add Common Applications Kept Enhanced (cake) qdisc")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260430061610.3503483-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>