ath9k: DFS - consider ext_channel pulses only in HT40 mode

The chip reports radar pulses on extension channel
even if operating in HT20 mode. This patch adds a
sanity check for HT40 mode before it feeds pulses
on extension channel to the pattern detector.
Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

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

@@ -198,7 +198,8 @@ void ath9k_dfs_process_phyerr(struct ath_softc *sc, void *data,
 	sc->dfs_prev_pulse_ts = pe.ts;
 	if (ard.pulse_bw_info & PRI_CH_RADAR_FOUND)
 		ath9k_dfs_process_radar_pulse(sc, &pe);
-	if (ard.pulse_bw_info & EXT_CH_RADAR_FOUND) {
+	if (IS_CHAN_HT40(ah->curchan) &&
+	    ard.pulse_bw_info & EXT_CH_RADAR_FOUND) {
 		pe.freq += IS_CHAN_HT40PLUS(ah->curchan) ? 20 : -20;
 		ath9k_dfs_process_radar_pulse(sc, &pe);
 	}