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

Change-Id: I363fa3e92140a5028dcb45e784dac87d1db64fac
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: I2e9f6a32579cdb43f9d8f2e5b1751af19d008a60