rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check

Since ca5ecddf (rcu: define __rcu address space modifier for sparse)
rcu_dereference_check use rcu_read_lock_held as a part of condition
automatically so callers do not have to do that as well.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

kernel/exit.c

@@ -85,7 +85,6 @@ static void __exit_signal(struct task_struct *tsk)
 	struct tty_struct *uninitialized_var(tty);
 
 	sighand = rcu_dereference_check(tsk->sighand,
-					rcu_read_lock_held() ||
 					lockdep_tasklist_lock_is_held());
 	spin_lock(&sighand->siglock);