Fix lcd not waking up when backlight is always off

This patch is relevant for targets with a transflective display.
If the backlight was set to "always off" (e.g. to use the lcd
in a pure passive way), and the sleep timer ran off, the LCD
would stay disabled and didn't wake up when a button is pressed.

Change-Id: I0a157c7f421d9fc4c7d8ba903f2cf93f6cef51d0
2 files changed