ath9k: make rfkill configurable

When the platform doesn't have rfkill support, i.e. nothing
is connected to the rfkill GPIO, there's little value in
polling the GPIO. Add a Kconfig option to allow disabling
the polling in ath9k.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/Kconfig

@@ -96,6 +96,16 @@ config ATH9K_LEGACY_RATE_CONTROL
 	  has to be passed to mac80211 using the module parameter,
 	  ieee80211_default_rc_algo.
 
+config ATH9K_RFKILL
+	bool "Atheros ath9k rfkill support" if EXPERT
+	depends on ATH9K
+	depends on RFKILL=y || RFKILL=ATH9K
+	default y
+	help
+	  Say Y to have ath9k poll the RF-Kill GPIO every couple of
+	  seconds. Turn off to save power, but enable it if you have
+	  a platform that can toggle the RF-Kill GPIO.
+
 config ATH9K_HTC
        tristate "Atheros HTC based wireless cards support"
        depends on USB && MAC80211

drivers/net/wireless/ath/ath9k/hw.c

@@ -2504,7 +2504,7 @@ int ath9k_hw_fill_cap_info(struct ath_hw *ah)
 	else
 		pCap->rts_aggr_limit = (8 * 1024);
 
-#if defined(CONFIG_RFKILL) || defined(CONFIG_RFKILL_MODULE)
+#ifdef CONFIG_ATH9K_RFKILL
 	ah->rfsilent = ah->eep_ops->get_eeprom(ah, EEP_RF_SILENT);
 	if (ah->rfsilent & EEP_RFSILENT_ENABLED) {
 		ah->rfkill_gpio =