OS-1574 libzdoor checks for NULL that cannot be

@@ -166,12 +166,12 @@
         if (zoneid < 0) {
                 zdoor_debug("zdoor_fattach: zoneid < 0");
                 return (ZDOOR_ARGS_ERROR);
         }
 
-        if (path == NULL) {
-                zdoor_debug("zdoor_fattach: NULL PATH");
+        if (service == NULL) {
+                zdoor_debug("zdoor_fattach: NULL service");
                 return (ZDOOR_ARGS_ERROR);
         }
 
         if ((tmpl_fd = init_template()) < 0) {
                 zdoor_warn("zdoor_fattach: init contract for %d:%s failed",