block: remove the disk and queue NULL checks in blkdev_issue_flush

Both of these never can be NULL for a live block device.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-flush.c

@@ -438,17 +438,9 @@ void blk_insert_flush(struct request *rq)
  */
 int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask)
 {
-	struct request_queue *q;
 	struct bio *bio;
 	int ret = 0;
 
-	if (bdev->bd_disk == NULL)
-		return -ENXIO;
-
-	q = bdev_get_queue(bdev);
-	if (!q)
-		return -ENXIO;
-
 	bio = bio_alloc(gfp_mask, 0);
 	bio_set_dev(bio, bdev);
 	bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;