expo: Support highlighting menu items

Expo normally uses a pointer to show the current item. Add support for
highlighting as well, since this makes it easier for the user to see the
current item.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/expo.h b/include/expo.h
index 16f2f18..dfecd6e 100644
--- a/include/expo.h
+++ b/include/expo.h
@@ -106,6 +106,7 @@
  * type set to EXPOACT_NONE if there is no action
  * @text_mode: true to use text mode for the menu (no vidconsole)
  * @popup: true to use popup menus, instead of showing all items
+ * @show_highlight: show a highlight bar on the selected menu item
  * @priv: Private data for the controller
  * @done: Indicates that a cedit session is complete and the user has quit
  * @save: Indicates that cedit data should be saved, rather than discarded
@@ -123,6 +124,7 @@
 	struct expo_action action;
 	bool text_mode;
 	bool popup;
+	bool show_highlight;
 	void *priv;
 	bool done;
 	bool save;