[menu] Fix default selection when default is item 0

Reported-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/hci/tui/menu_ui.c

 	ui.timeout = ( ( timeout_ms * TICKS_PER_SEC ) / 1000 );
 	list_for_each_entry ( item, &menu->items, list ) {
 		if ( item->label ) {
-			labelled_count++;
-			if ( ! ui.selected )
+			if ( ! labelled_count )
 				ui.selected = ui.count;
+			labelled_count++;
 			if ( item->is_default )
 				ui.selected = ui.count;
 		}