ath9k: do not overwrite ACK timeout estimation

Do not overwrite ACK timeout estimation in ath9k_hw_init_global_settings() if
dynack processing has been enabled

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index e71f824..949d5d6 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1055,6 +1055,14 @@
 		ctstimeout += 48 - sifstime - ah->slottime;
 	}
 
+	if (ah->dynack.enabled) {
+		acktimeout = ah->dynack.ackto;
+		ctstimeout = acktimeout;
+		slottime = (acktimeout - 3) / 2;
+	} else {
+		ah->dynack.ackto = acktimeout;
+	}
+
 	ath9k_hw_set_sifs_time(ah, sifstime);
 	ath9k_hw_setslottime(ah, slottime);
 	ath9k_hw_set_ack_timeout(ah, acktimeout);