ath6kl: iw dev wlan0 link implementation

implementing the cfg ops that gets called when iw dev wlan0
link is issued by user. The ops that needs to be implemented
is get_station.

kvalo: check the mac address, remove signal_pending(), use ARRAY_SIZE()
and fix style issues

Signed-off-by: Naveen Singh <nsingh@atheros.com>
Signed-off-by: Kalle Valo <kalle.valo@atheros.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>