rculist: fix borked __list_for_each_rcu() macro

This restores parentheses blance.
Signed-off-by: Mariusz Kozlowski <mk@lab.zgora.pl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

include/linux/rculist.h

@@ -244,7 +244,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
 #define __list_for_each_rcu(pos, head) \
 	for (pos = rcu_dereference_raw(list_next_rcu(head)); \
 		pos != (head); \
-		pos = rcu_dereference_raw(list_next_rcu((pos)))
+		pos = rcu_dereference_raw(list_next_rcu(pos)))
 
 /**
  * list_for_each_entry_rcu	-	iterate over rcu list of given type