rcu: Remove dead code from rcu_segcblist_insert_pend_cbs()

The rcu_segcblist_insert_pend_cbs() function currently (partially)
initializes the rcu_cblist that it pulls callbacks from.  However, all
the resulting stores are dead because all callers pass in the address of
an on-stack cblist that is not used afterwards.  This commit therefore
removes this pointless initialization.
Signed-off-by: NPaul E. McKenney <paulmck@kernel.org>

kernel/rcu/rcu_segcblist.c

@@ -381,8 +381,6 @@ void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
 		return; /* Nothing to do. */
 	WRITE_ONCE(*rsclp->tails[RCU_NEXT_TAIL], rclp->head);
 	WRITE_ONCE(rsclp->tails[RCU_NEXT_TAIL], rclp->tail);
-	rclp->head = NULL;
-	rclp->tail = &rclp->head;
 }
 
 /*