Bug 15378: Allow removal of lost items from course reserves

Bug 15378: Allow removal of lost items from course reserves

It seems that this restriction is not necessary, it should be possible
to remove lost items from course reserves.

Test plan:
Create a course and add reserve with a lost item

=> Without this patch the "Remove" button is disabled and the item
cannot be removed from the course
=> With this patch applied the button is enable and the item can be
removed

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>