md: raid0: make hash_spacing and preshift sector-based.

This patch renames the hash_spacing and preshift members of struct
raid0_private_data to spacing and sector_shift respectively and
changes the semantics as follows:

We always have spacing = 2 * hash_spacing. In case
sizeof(sector_t) > sizeof(u32) we also have sector_shift = preshift + 1
while sector_shift = preshift = 0 otherwise.

Note that the values of nb_zone and zone are unaffected by these changes
because in the sector_div() preceeding the assignement of these two
variables both arguments double.

Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/include/linux/raid/raid0.h b/include/linux/raid/raid0.h
index c12521d0..fd42aa8 100644
--- a/include/linux/raid/raid0.h
+++ b/include/linux/raid/raid0.h
@@ -19,8 +19,8 @@
 	mdk_rdev_t **devlist; /* lists of rdevs, pointed to by strip_zone->dev */
 	int nr_strip_zones;
 
-	sector_t hash_spacing;
-	int preshift;			/* shift this before divide by hash_spacing */
+	sector_t spacing;
+	int sector_shift; /* shift this before divide by spacing */
 };
 
 typedef struct raid0_private_data raid0_conf_t;