ath9k: Use CONFIG_ATH9K_BTCOEX_SUPPORT

This patch uses CONFIG_ATH9K_BTCOEX_SUPPORT to conditionally
compile btcoex-related code in the driver core.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/gpio.c b/drivers/net/wireless/ath/ath9k/gpio.c
index e870251..77b3eb7 100644
--- a/drivers/net/wireless/ath/ath9k/gpio.c
+++ b/drivers/net/wireless/ath/ath9k/gpio.c
@@ -110,6 +110,8 @@
 		wiphy_rfkill_start_polling(sc->hw->wiphy);
 }
 
+#ifdef CONFIG_ATH9K_BTCOEX_SUPPORT
+
 /******************/
 /*     BTCOEX     */
 /******************/
@@ -423,3 +425,5 @@
 
 	return 0;
 }
+
+#endif /* CONFIG_ATH9K_BTCOEX_SUPPORT */