ath6kl: add support for WPS

Add control flag CONNECT_WPS_FLAG if a WPS IE is present in the
Association Request IEs. This flag is needed when the station must
connect to a WPS-enabled AP.

Signed-off-by: Aarthi Thiruvengadam <athiruve@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>