ath5k: Increase "fudge" for beacon timers

We use FUDGE to make sure the next TBTT is ahead of the current TU.
Since we later substract AR5K_TUNE_SW_BEACON_RESP (10) in the timer
configuration we need to make sure it is bigger than that.
Signed-off-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/base.c

@@ -1886,8 +1886,11 @@ ath5k_beacon_update_timers(struct ath5k_softc *sc, u64 bc_tsf)
 	hw_tsf = ath5k_hw_get_tsf64(ah);
 	hw_tu = TSF_TO_TU(hw_tsf);
 
-#define FUDGE 3
-	/* we use FUDGE to make sure the next TBTT is ahead of the current TU */
+#define FUDGE AR5K_TUNE_SW_BEACON_RESP + 3
+	/* We use FUDGE to make sure the next TBTT is ahead of the current TU.
+	 * Since we later substract AR5K_TUNE_SW_BEACON_RESP (10) in the timer
+	 * configuration we need to make sure it is bigger than that. */
+
 	if (bc_tsf == -1) {
 		/*
 		 * no beacons received, called internally.