btrfs: make btrfs_destroy_delayed_refs use btrfs_delete_ref_head

Instead of open coding this stuff use the helper instead.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -4264,12 +4264,7 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
 		if (head->must_insert_reserved)
 			pin_bytes = true;
 		btrfs_free_delayed_extent_op(head->extent_op);
-		delayed_refs->num_heads--;
-		if (head->processing == 0)
-			delayed_refs->num_heads_ready--;
-		atomic_dec(&delayed_refs->num_entries);
-		rb_erase_cached(&head->href_node, &delayed_refs->href_root);
-		RB_CLEAR_NODE(&head->href_node);
+		btrfs_delete_ref_head(delayed_refs, head);
 		spin_unlock(&head->lock);
 		spin_unlock(&delayed_refs->lock);
 		mutex_unlock(&head->mutex);