ath9k: Fix wlan-active gpio for the AR9003 family

When disabling BTCOEX, clearing the wlanactive gpio line
is required only for pre-AR9003 cards.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>