[POWERPC] Fix viodasd geometry calculations

Commit a885c8c4 that introduced the
getgeo block device method changed the fallback number of sectors and
introduced a bug into the fallback cylinder number calculation.

Thanks to Rusty Russell for noticing this.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

drivers/block/viodasd.c

@@ -252,10 +252,10 @@ static int viodasd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 	struct gendisk *disk = bdev->bd_disk;
 	struct viodasd_device *d = disk->private_data;
 
-	geo->sectors = d->sectors ? d->sectors : 0;
+	geo->sectors = d->sectors ? d->sectors : 32;
 	geo->heads = d->tracks ? d->tracks  : 64;
 	geo->cylinders = d->cylinders ? d->cylinders :
-		get_capacity(disk) / (geo->cylinders * geo->heads);
+		get_capacity(disk) / (geo->sectors * geo->heads);
 
 	return 0;
 }