n64: use sector SECTOR_SHIFT instead 512

Instead of using magic numbers use SECTOR_SHIFT to get the number of
sectors from the size.
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Lauri Kasanen <cand@gmx.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

drivers/block/n64cart.c

@@ -157,7 +157,7 @@ static int __init n64cart_probe(struct platform_device *pdev)
 	disk->fops = &n64cart_fops;
 	strcpy(disk->disk_name, "n64cart");
 
-	set_capacity(disk, size / 512);
+	set_capacity(disk, size >> SECTOR_SHIFT);
 	set_disk_ro(disk, 1);
 
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, queue);