ath9k_hw: Fix radio retention for AR9462

IQ calibration during fast channel change sometimes failed
with RTT. And also restoring invalid radio retention readings
during init cal could cause failure to set the channel properly.
This patch counts the valid rtt history readings and clears
rtt mask.
Signed-off-by: NRajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ar9003_calib.c

@@ -908,12 +908,15 @@ static bool ar9003_hw_rtt_restore(struct ath_hw *ah, struct ath9k_channel *chan)
 	int i;
 	bool restore;
 
-	if (!(ah->caps.hw_caps & ATH9K_HW_CAP_RTT) || !ah->caldata)
+	if (!ah->caldata)
 		return false;
 
 	hist = &ah->caldata->rtt_hist;
+	if (!hist->num_readings)
+		return false;
+
 	ar9003_hw_rtt_enable(ah);
-	ar9003_hw_rtt_set_mask(ah, 0x10);
+	ar9003_hw_rtt_set_mask(ah, 0x00);
 	for (i = 0; i < AR9300_MAX_CHAINS; i++) {
 		if (!(ah->rxchainmask & (1 << i)))
 			continue;
@@ -1070,6 +1073,7 @@ static bool ar9003_hw_init_cal(struct ath_hw *ah,
 		if (is_reusable && (hist->num_readings < RTT_HIST_MAX)) {
 			u32 *table;
 
+			hist->num_readings++;
 			for (i = 0; i < AR9300_MAX_CHAINS; i++) {
 				if (!(ah->rxchainmask & (1 << i)))
 					continue;