mac80211: don't calculate duration for S1G

For now just skip the duration calculation for frames
transmitted on the S1G band and avoid a warning.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
Link: https://lore.kernel.org/r/20200922022818.15855-11-thomas@adapt-ip.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/tx.c

@@ -82,6 +82,10 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
 
 	erp = txrate->flags & IEEE80211_RATE_ERP_G;
 
+	/* device is expected to do this */
+	if (sband->band == NL80211_BAND_S1GHZ)
+		return 0;
+
 	/*
 	 * data and mgmt (except PS Poll):
 	 * - during CFP: 32768