btrfs: remove unnecessary list_del

We can safely iterate whole list items, without using list_del macro.
So remove the list_del call.
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Byongho Lee <bhlee.kernel@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -2599,7 +2599,6 @@ static void free_sa_defrag_extent(struct new_sa_defrag_extent *new)
 		return;
 
 	list_for_each_entry_safe(old, tmp, &new->head, list) {
-		list_del(&old->list);
 		kfree(old);
 	}
 	kfree(new);