bpf: no longer acquire map_idr_lock in bpf_map_inc_not_zero()

bpf: no longer acquire map_idr_lock in bpf_map_inc_not_zero()

bpf_sk_storage_clone() is the only caller of bpf_map_inc_not_zero()
and is holding rcu_read_lock().

map_idr_lock does not add any protection, just remove the cost
for passive TCP flows.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Kui-Feng Lee <kuifeng@meta.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/r/20250301191315.1532629-1-edumazet@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>