LP1665052: Fix checkin workstation display on recent circs view

LP1665052: Fix checkin workstation display on recent circs view

To test:
1) Go to Item Status > Detail View > Recent Circ History for
an item that is currently checked out.
2) Note that the Checkin Workstation field says
"{{circ.checkin_workstation.name()}}"
3) Apply this commit.
4) Note that the Checkin Workstation field is empty if an
item is an item hasn't been checked in, but is filled with
the appropriate workstation name after it has been checked
in.

Signed-off-by: Jane Sandberg <sandbej@linnbenton.edu>
Signed-off-by: Ben Shum <ben@evergreener.net>