lockup detector: Fix grammar by adding a missing "to" in the comments

This fixes a minor grammar problem in the comments in
hung_task.c

Signed-off-by: John Kacur <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
LKML-Reference: <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>

kernel/hung_task.c

···
  * periodically exit the critical section and enter a new one.
  *
  * For preemptible RCU it is sufficient to call rcu_read_unlock in order
- * exit the grace period. For classic RCU, a reschedule is required.
+ * to exit the grace period. For classic RCU, a reschedule is required.
  */
 static void rcu_lock_break(struct task_struct *g, struct task_struct *t)
 {