tests: fix another test failure in test/du/inodes.sh

tests: fix another test failure in test/du/inodes.sh

Prompted by the continuous integration build failure at:
http://hydra.nixos.org/build/5584121

du(1) uses the first file object of the two test files linked to the
same inode, 'd/f' and 'd/h', whatever the system returns first.
Use 'd/f' in both the expected and the actual output.

* test/du/inodes.sh: Change the expected output as described above
when returning the --all directory entries (without -l).  Also replace
the name of the hardlink 'd/h' by 'd/f' in the actual output.