btrfs: make btrfs_readdir_delayed_dir_index() return a bool instead

btrfs: make btrfs_readdir_delayed_dir_index() return a bool instead

There's no need to return errors, all we do is return 1 or 0 depending
on whether we should or should not stop iterating over delayed dir
indexes. So change the function to return bool instead of an int.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>