ath9k: enable ANI to help with noisy environments

This enables Adaptive Noise Immunity (ANI) on ath9k.
ANI is as algorithm designed to minimize the detrimental
effects of time-varying interferences. This should
help with throughput in noisy environments. To use
ANI we re-enable the MIB interrupt. Since ANI works
on a timer and updates the noise floor we take
advantage of this and also report a non-static noise
floor now to mac80211.

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: Jouni Malinen <Jouni.Malinen@Atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/ath9k.h b/drivers/net/wireless/ath9k/ath9k.h
index 0e897c2..accace5 100644
--- a/drivers/net/wireless/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath9k/ath9k.h
@@ -854,7 +854,7 @@
 			u8 rxchainmask,
 			bool longcal,
 			bool *isCalDone);
-int16_t ath9k_hw_getchan_noise(struct ath_hal *ah,
+s16 ath9k_hw_getchan_noise(struct ath_hal *ah,
 			       struct ath9k_channel *chan);
 void ath9k_hw_write_associd(struct ath_hal *ah, const u8 *bssid,
 			    u16 assocId);