ath9k: Enable WLAN/BT Ant Diversity for WB225/WB195

A custom solution for Asus is WB195 based and supports
WLAN/BT Rx diversity. Identify this card and set the
capability.

CUS198/CUS230, which are based on WB225 also support
WLAN/BT Rx diversity.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>