bfq-iosched: don't call bfqg_and_blkg_put for !CONFIG_BFQ_GROUP_IOSCHED

It's not available if we don't have group io scheduling set, and
there's no need to call it.

Fixes: 0d52af5 ("block, bfq: release oom-queue ref to root group on exit")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bfq-iosched.c

@@ -4893,10 +4893,10 @@ static void bfq_exit_queue(struct elevator_queue *e)
 
 	hrtimer_cancel(&bfqd->idle_slice_timer);
 
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
 	/* release oom-queue reference to root group */
 	bfqg_and_blkg_put(bfqd->root_group);
 
-#ifdef CONFIG_BFQ_GROUP_IOSCHED
 	blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq);
 #else
 	spin_lock_irq(&bfqd->lock);