net_sched: sch_hhf: annotate data-races in hhf_dump_stats()

net_sched: sch_hhf: annotate data-races in hhf_dump_stats()

hhf_dump_stats() only runs with RTNL held,
reading fields that can be changed in qdisc fast path.

Add READ_ONCE()/WRITE_ONCE() annotations.

Fixes: edb09eb17ed8 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260421143349.4052215-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>