Bug 20067: Fix false display of authorised value for materials on staff detail page

Bug 20067: Fix false display of authorised value for materials on staff detail page

Koha didn't check for a linked authorised value category for
Koha didn't check for a linked authorised value category for
items.materials correctly which led to displaying false information
on the detail page.

To test:
- before applying the patch:
- make sure sample data and configuration is loaded
- edit any item
- write 2 in the $3 materials specificed
- check the details page normal view - it will display 'restocking'
- apply patch
- check display, it should now show "2"
- link 952$3 (MARC21) to ORDER_CANCELLATION_REASON
- check display again, it should now show 'restocking'

Signed-off-by: Jesse Maseto <jesse@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>