ath9k: Add TSFOOR interrupt stats in debug info

This helped the developers to fix an issue of chip not entering network
sleep during idle state, previously this was only available as a debug
message

Signed-off-by: Mohammed Shafi Shajakhan <mshajakhan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/debug.h b/drivers/net/wireless/ath/ath9k/debug.h
index 1f9f8ea..5488a32 100644
--- a/drivers/net/wireless/ath/ath9k/debug.h
+++ b/drivers/net/wireless/ath/ath9k/debug.h
@@ -54,6 +54,9 @@
  * @dtimsync: DTIM sync lossage
  * @dtim: RX Beacon with DTIM
  * @bb_watchdog: Baseband watchdog
+ * @tsfoor: TSF out of range, indicates that the corrected TSF received
+ * from a beacon differs from the PCU's internal TSF by more than a
+ * (programmable) threshold
  */
 struct ath_interrupt_stats {
 	u32 total;
@@ -78,6 +81,7 @@
 	u32 dtimsync;
 	u32 dtim;
 	u32 bb_watchdog;
+	u32 tsfoor;
 };
 
 /**