net: netrom: Add missing annotation for nr_neigh_start()

Sparse reports a warning at nr_neigh_start()
warning: context imbalance in nr_neigh_start() - wrong count at exit
The root cause is the missing annotation at nr_neigh_start()
Add the missing __acquires(&nr_neigh_list_lock) annotation

Signed-off-by: Jules Irenge <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/netrom/nr_route.c

···
 };
 
 static void *nr_neigh_start(struct seq_file *seq, loff_t *pos)
+	__acquires(&nr_neigh_list_lock)
 {
 	spin_lock_bh(&nr_neigh_list_lock);
 	return seq_hlist_start_head(&nr_neigh_list, *pos);