btrfs: remove stale comment from btrfs_flush_all_pending_stuffs

Commit fcebe4562dec83b3f8d3088d77584727b09130b2 (Btrfs: rework qgroup
accounting) removed the qgroup accounting after delayed refs.

Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/transaction.c

@@ -1617,11 +1617,6 @@ static int btrfs_flush_all_pending_stuffs(struct btrfs_trans_handle *trans,
 	int ret;
 
 	ret = btrfs_run_delayed_items(trans, root);
-	/*
-	 * running the delayed items may have added new refs. account
-	 * them now so that they hinder processing of more delayed refs
-	 * as little as possible.
-	 */
 	if (ret)
 		return ret;