md: revert the recent addition of a call to the BLKRRPART ioctl.

It turns out that it is only safe to call blkdev_ioctl when the device
is actually open (as ->bd_disk is set to NULL on last close).  And it
is quite possible for do_md_stop to be called when the device is not
open.  So discard the call to blkdev_ioctl(BLKRRPART) which was
added in
   commit 934d9c23b4c7e31840a895ba4b7e88d6413c81f3

It is just as easy to call this ioctl from userspace when needed (on
mdadm -S) so leave it out of the kernel

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -3884,7 +3884,6 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
 	if (mode == 0) {
 		mdk_rdev_t *rdev;
 		struct list_head *tmp;
-		struct block_device *bdev;
 
 		printk(KERN_INFO "md: %s stopped.\n", mdname(mddev));
 
@@ -3941,11 +3940,6 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
 		mddev->degraded = 0;
 		mddev->barriers_work = 0;
 		mddev->safemode = 0;
-		bdev = bdget_disk(mddev->gendisk, 0);
-		if (bdev) {
-			blkdev_ioctl(bdev, 0, BLKRRPART, 0);
-			bdput(bdev);
-		}
 		kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
 
 	} else if (mddev->pers)