1. X5 lcd sleep
2. #define HAVE_LCD_ENABLE
3. add "backlight (on hold switch)" setting, adapted from FS #5735
Note that the while(1) yield ==> asm("halt") part is NOT commited here,
I prefer it would be discussed separately.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10489 a1c6a512-1295-4272-9138-f99709370657