mtip32xx: Remove dfs_parent after pci unregister

In module exit, dfs_parent and it's subtree were removed before
unregistering with pci. When debugfs entry for each device is attempted
to remove in pci_remove() context, they don't exist, as dfs_parent and
its children were already ripped apart.

Modified to first unregister with pci and then remove dfs_parent.
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>

(cherry picked from commit af5ded8c)
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

drivers/block/mtip32xx/mtip32xx.c

@@ -4282,13 +4282,13 @@ static int __init mtip_init(void)
  */
 static void __exit mtip_exit(void)
 {
-	debugfs_remove_recursive(dfs_parent);
-
 	/* Release the allocated major block device number. */
 	unregister_blkdev(mtip_major, MTIP_DRV_NAME);
 
 	/* Unregister the PCI driver. */
 	pci_unregister_driver(&mtip_pci_driver);
+
+	debugfs_remove_recursive(dfs_parent);
 }
 
 MODULE_AUTHOR("Micron Technology, Inc");