ath9k_hw: fix periodic noise floor calibration on AR9003

The periodic noise floor calibration is broken on this chip family, because
it keeps triggering a software-filtered noise floor calibration, but never
reads the result before uploading the history buffer value to the hardware.

Fix this with a call to ath9k_hw_getnf(), just like on AR9002.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Acked-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/ar9003_calib.c b/drivers/net/wireless/ath/ath9k/ar9003_calib.c
index 938365e..f51ab89 100644
--- a/drivers/net/wireless/ath/ath9k/ar9003_calib.c
+++ b/drivers/net/wireless/ath/ath9k/ar9003_calib.c
@@ -149,6 +149,12 @@
 	/* Do NF cal only at longer intervals */
 	if (longcal) {
 		/*
+		 * Get the value from the previous NF cal and update
+		 * history buffer.
+		 */
+		ath9k_hw_getnf(ah, chan);
+
+		/*
 		 * Load the NF from history buffer of the current channel.
 		 * NF is slow time-variant, so it is OK to use a historical
 		 * value.