md: fix return value of rdev_size_change()

When trying to grow an array by enlarging component devices,
rdev_size_store() expects the return value of rdev_size_change() to be
in sectors, but the actual value is returned in KBs.

This functionality was broken by commit
dd8ac336c13fd8afdb082ebacb1cddd5cf727889
so this patch is suitable for any kernel since 2.6.30.

Cc: [e-mail]
Signed-off-by: Justin Maggard <[e-mail]>
Signed-off-by: NeilBrown <[e-mail]>

drivers/md/md.c

···
 	md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
 		       rdev->sb_page);
 	md_super_wait(rdev->mddev);
-	return num_sectors / 2; /* kB for sysfs */
+	return num_sectors;
 }
 
 
···
 	md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
 		       rdev->sb_page);
 	md_super_wait(rdev->mddev);
-	return num_sectors / 2; /* kB for sysfs */
+	return num_sectors;
 }
 
 static struct super_type super_types[] = {