LU-3025 hsm-llapi: bad type cast in llapi_hsm_copytool_fini()

Correct a wrong type cast in llapi_hsm_copytool_fini()

Signed-off-by: JC Lafoucriere <jacques-charles.lafoucriere@cea.fr>
Change-Id: Iebe4a36178afdfad8b99140efd6b3afc8b9eb942
Reviewed-on: http://review.whamcloud.com/5837
Reviewed-by: John Hammond <johnlockwoodhammond@gmail.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>