partitions/efi: use bdev_nr_bytes instead of open coding it

Use the proper helper to read the block device size.

Signed-off-by: Christoph Hellwig <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

block/partitions/efi.c

···
  */
 static u64 last_lba(struct gendisk *disk)
 {
-	return div_u64(disk->part0->bd_inode->i_size,
+	return div_u64(bdev_nr_bytes(disk->part0),
 		       queue_logical_block_size(disk->queue)) - 1ULL;
 }