Bug 18320: Remove patroncards/edit-layout.pl warnings

Bug 18320: Remove patroncards/edit-layout.pl warnings

This patch removes warnings generated by the script itself.

To test:
- Go to Tools › Patron card creator › Manage layouts and
        Tools › Patron card creator › New layout
- Add a new layout, adit existing.
=> FAIL: Warnings logged by edit-layout.pl
- Apply this patch
- Go to Tools › Patron card creator › Manage layouts and
        Tools › Patron card creator › New layout
- Add a new layout, adit existing.
=> SUCCESS: No warnings generated by edit-layout.pl
- Sign off :-D

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>