Bug 15431: svc/checkouts dies due to undefined variable (13024 merge problem)

Bug 15431: svc/checkouts dies due to undefined variable (13024 merge problem)

When bug 13024 was merged into 3.20.x, a bug was introduced by replacing the
old way to fetch itemtype descriptions with the newer (3.22+).

To test:
- Perform a checkout on a patron
- Check so all checkouts are shown immediately
=> FAIL: It keeps loading forever. The logs show the svc/checkouts script died
- Apply the patch
- Reload page
=> SUCCESS: It loads the circ information correctly
- Sign off :-D

Regards

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>