Changed the functioncall of free(..) to osp_credential_free(..)

in manage.c: Changed the call of free(osp_credential) to
  osp_credential_free(osp_credential) in function
  target_osp_ssh_credential(..).

(cherry picked from commit c9e5d28)

src/manage.c

@@ -2145,15 +2145,15 @@ target_osp_ssh_credential (target_t target)
             {
               g_warning ("%s: SSH Elevate Credential not found.", __func__);
               cleanup_iterator (&ssh_elevate_iter);
-              free(osp_credential);
+              osp_credential_free(osp_credential);
               return NULL;
             }
           elevate_type = credential_iterator_type (&ssh_elevate_iter);
           if (strcmp (elevate_type, "up"))
             {
               g_warning ("%s: SSH Elevate Credential not of type up", __func__);
               cleanup_iterator (&ssh_elevate_iter);
-              free(osp_credential);
+              osp_credential_free(osp_credential);
               return NULL;
             }
           osp_credential_set_auth_data (osp_credential,