Add backlight class support to the eeepc-laptop driver.
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NLen Brown <len.brown@intel.com>

This patch is based on Eric Cooper's work to clean the original asus_acpi
given by Asus.  It's a platform driver (/sys/devices/platform/eeepc/)
wich support:
     - hotkeys - wlan on/off - camera on/off - cardr on/off
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NLen Brown <len.brown@intel.com>