rcu: Fix typo in PER_RCU_NODE_PERIOD header comment

This commit just changes a "the the" to "the" to reduce repetition.

Reported-by: Michalis Kokologiannakis <mixaskok@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7c23860..b1679e8 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -199,7 +199,7 @@ static const int gp_cleanup_delay;
 
 /*
  * Number of grace periods between delays, normalized by the duration of
- * the delay.  The longer the the delay, the more the grace periods between
+ * the delay.  The longer the delay, the more the grace periods between
  * each delay.  The reason for this normalization is that it means that,
  * for non-zero delays, the overall slowdown of grace periods is constant
  * regardless of the duration of the delay.  This arrangement balances