ath9k: Reintroduce modparam to enable btcoex

It is not ideal to enable btcoex based on subsys id as it is
not unique, they are so random. It is also a pain keeping
all of them in a table to enable btcoex for a particular
hw. Going back to the old idea.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index 7eef1fa..d11e6da 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -38,6 +38,10 @@
 module_param_named(blink, led_blink, int, 0444);
 MODULE_PARM_DESC(blink, "Enable LED blink on activity");
 
+static int ath9k_btcoex_enable;
+module_param_named(btcoex_enable, ath9k_btcoex_enable, int, 0444);
+MODULE_PARM_DESC(btcoex_enable, "Enable wifi-BT coexistence");
+
 /* We use the hw_value as an index into our private channel structure */
 
 #define CHAN2G(_freq, _idx)  { \
@@ -543,6 +547,7 @@
 	common->hw = sc->hw;
 	common->priv = sc;
 	common->debug_mask = ath9k_debug;
+	common->btcoex_enabled = ath9k_btcoex_enable == 1;
 	spin_lock_init(&common->cc_lock);
 
 	spin_lock_init(&sc->wiphy_lock);