don't use ->bd_inode to access the block device size v3

[Christoph Hellwig]

On Mon, Oct 18, 2021 at 11:40:51AM -0600, Jens Axboe wrote:
>  static inline loff_t bdev_nr_bytes(struct block_device *bdev)
>  {
> -	return i_size_read(bdev->bd_inode);
> +	return bdev->bd_nr_sectors;

This hunk needs to go into bdev_nr_sectors, and the bdev_nr_bytes
probably wants to call bdev_nr_sectors and do the shifting.