Bug 36053: Correct input name for item replacement fields

Bug 36053: Correct input name for item replacement fields

To test:
1 - Follow test plan and use sample record from bug 35912 ( or similar)
2 - Confirm that when the order is saved the replacement price is $0.00
3 - Apply patch, restart_all
4 - Delete previous orders, and stage and add to basket again
5 - Confirm that upon adding orders to basket the replacement price is saved correctly

Signed-off-by: Brendan Lawlor <blawlor@clamsnet.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>