lockdep: Replace synchronize_sched() with synchronize_rcu()

Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can be
replaced by synchronize_rcu().  This commit therefore makes this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>

kernel/locking/lockdep.c

@@ -4195,7 +4195,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
 	 *
 	 * sync_sched() is sufficient because the read-side is IRQ disable.
 	 */
-	synchronize_sched();
+	synchronize_rcu();
 
 	/*
 	 * XXX at this point we could return the resources to the pool;