ath5k: disable beacon filter when station is not associated

Ath5k driver has too many interrupts per second at idle
http://bugzilla.kernel.org/show_bug.cgi?id=11749

Signed-off-by: Martin Xu <martin.xu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath5k/base.h b/drivers/net/wireless/ath5k/base.h
index 06d1054..facc60d 100644
--- a/drivers/net/wireless/ath5k/base.h
+++ b/drivers/net/wireless/ath5k/base.h
@@ -179,6 +179,7 @@
 
 	struct timer_list	calib_tim;	/* calibration timer */
 	int 			power_level;	/* Requested tx power in dbm */
+	bool			assoc;		/* assocate state */
 };
 
 #define ath5k_hw_hasbssidmask(_ah) \