Fixed a typographical mistake

The argument should be the device struct, not an sprog_data struct.

sprog.c

@@ -56,7 +56,7 @@ void sprog_process(const struct sprog_family *fam, void *arg, const struct sprog
     fam->exec(arg, d);
   else if(mode==2) {
     fam->write(arg, d);
-    fam->close(d);
+    fam->close(arg);
   }
 }