AVR LED: Light up on IRQ, shut down after 10s

The only thing that is drastically different for now from the stock kernel is
that the keypad LEDs are kept on while the screen is on. These LEDs are draining
the battery, so the driver should enable LEDs on keyboard IRQ and disable them
after 10 seconds in order to become a perfect drop-in replacement for stock
2.6.29 kernel. Fixes #14