Bug 15092: (followup) Descriptions not show for search categories

Bug 15092: (followup) Descriptions not show for search categories

If we have some item types in search categories, description
is not show in opac advanced search

To test:
1) Add some item type to a search category
2) Go to OPAC > Advanced search
empty description for that category
3) Apply the patch
4) Repeat 2), description must be present

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>