asus-laptop: use select instead of depends on

Like thinkpad_acpi or eeepc-laptop, asus-laptop will
now use "select" instead of "depends on"
for LEDS_CLASS, NEW_LEDS and BACKLIGHT_CLASS_DEVICE

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Len Brown <len.brown@intel.com>