net_sched: act: remove tcfa_qstats

tcfa_qstats is currently only used to hold drops and overlimits counters.

tcf_action_inc_drop_qstats() and tcf_action_inc_overlimit_qstats()
currently acquire a->tcfa_lock to increment these counters.

Switch to two atomic_t to get lock-free accounting.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20250901093141.2093176-1-edumazet@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>