cypress-touchkey : add sysfs interface to enable/disable lighting hardwarekey backlight on screen touch (Yank555.lu)

Change-Id: Ie8810749d21ab94a76618864afe4832f1309f8b7
cypress-touchkey : add sysfs interface to enable/disable lighting hardwarekey backlight on screen touch (Yank555.lu)

- prevent h/w keys to light up on late_resume as well if disabled

Change-Id: If4b03cd3f5392c898a05bac92c8c830e532e6785