Bug 26438: Rename temporary Koha::Item variables to avoid conflict

Bug 26438: Rename temporary Koha::Item variables to avoid conflict

Returns from Koha::Item calls were stored in temporary variables
called $item. Unfortunately they occur in routines already with
an $item variable holding a lineitem and hide that variable although
only required for two lines of code. An error occurs if girfield
is called on the wrong variable. Renamed all three occurences
of $item to $kitem to avoid the error

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>