md: Removing num_sector and replacing start_sector with end_sector

Remove num_sectors from dev_info and replace start_sector with
end_sector.  This makes a lot of comparisons much simpler.

Signed-off-by: Sandeep K Sinha <sandeepksinha@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/linear.h b/drivers/md/linear.h
index 721a878..599e5c1 100644
--- a/drivers/md/linear.h
+++ b/drivers/md/linear.h
@@ -3,8 +3,7 @@
 
 struct dev_info {
 	mdk_rdev_t	*rdev;
-	sector_t	num_sectors;
-	sector_t	start_sector;
+	sector_t	end_sector;
 };
 
 typedef struct dev_info dev_info_t;