package: fix call to Insertstorage_domain_static

This patch updates inst_add_iso_storage_domain to call
Insertstorage_domain_static with a free text argument which was
introduced in 5367a779fa78c811637350aaba895f54b425d85d

Change-Id: I2bc8ca849ef1e65285993b9c5f4cee3de0deea74
Signed-off-by: Doron Fediuck <dfediuck@redhat.com>