Bug 17345: Fix typo in sysprefs.sql

Bug 17345: Fix typo in sysprefs.sql

This fixes a tiny typo in sysprefs.sql that kept all
systempreferences from being installed.

To test:
- Create a new koha database, run the web installer
- Verify that all systempreferences have been loaded
  select count(*) from systempreferences should be
  no less than 553

or

- Truncate your systempreferences table
- Verify that the repaired sysprefs.sql file loads
  without error

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>