Use user preferred touchscreen mode in 'Main Menu Config' plugin instead of defaulting to 'button' mode.

Motivation:

1. 'Absolute point' mode works fine in this plugin.
2. This plugin is part of the Rockbox menus. If the user setting is not 'button' mode, it is unexpected to have only this menu work in a different mode compared to all other menus.

Change-Id: Iec91d3cd875e8a80e835a4a58d87a6ec84529def

apps/plugins/main_menu_config.c

@@ -192,6 +192,10 @@ enum plugin_status plugin_start(const void* parameter)
     rb->gui_synclist_draw(&list);
     rb->gui_synclist_speak_item(&list);
 
+#ifdef HAVE_TOUCHSCREEN
+    rb->touchscreen_set_mode(rb->global_settings->touch_mode);
+#endif
+
     while (!done)
     {
         cur_sel = rb->gui_synclist_get_sel_pos(&list);