elevator: remove redundant code in elv_unregister_queue()

"elevator_queue *e" is already declared and initialized in the beginning
of elv_unregister_queue().
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221019121518.3865235-2-yukuai1@huaweicloud.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/elevator.c

@@ -524,8 +524,6 @@ void elv_unregister_queue(struct request_queue *q)
 	lockdep_assert_held(&q->sysfs_lock);
 
 	if (e && e->registered) {
-		struct elevator_queue *e = q->elevator;
-
 		kobject_uevent(&e->kobj, KOBJ_REMOVE);
 		kobject_del(&e->kobj);