scripts: fix invalid path in dcache-pool-meta-preupgrade

Acked-by: Gerd Behrmann
Target: trunk, 2.6
Require-book: no
Require-notes: no
chimera:  fix corruption of directory mode on tag update

in case up create/update of a directory tag, the directory mode was
corrupted as  setInodeAttributes was used.

This is a simple fix before the complete set/get attribute rewrite.

Acked-by: Gerd Behrmann
Target: trunk, 2.6
Require-book: no
Require-notes: yes