[POWERPC] Fix viodasd geometry calculations

Commit a885c8c4316e1c1d2d2c8755da3f3d14f852528d 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>
diff --git a/drivers/block/viodasd.c b/drivers/block/viodasd.c
index 68592c3..dae3991 100644
--- a/drivers/block/viodasd.c
+++ b/drivers/block/viodasd.c
@@ -252,10 +252,10 @@
 	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;
 }