asus-laptop: add bluetooth and wlan support

WLED and BLED are not handled like other leds (MLED, etc ..),
because sometime they also control the wlan/bluetooth device.
If the method for wireless_status is found, it's used to get the
status, otherwise hotk->status is used.  We also use the HWRS
method, which tell if the bluetooth/wlan device is present or not.
This patch show why we need a ASUS_SET_DEVICE_ATTR macro : if
there is a bluetooth device, /sys/dev.../asus-laptop/bluetooth
is usable, else it's not but it's clean.

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