ath10k: clear tx status before submitting to mac80211

Garbage was reported in ieee80211_tx_info. This
led to a WARN_ON in cfg80211_calculate_bitrate().

This also fixes some random tx bitrate values
reported through `iw` command.
Reported-By: NKalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: NMichal Kazior <michal.kazior@tieto.com>
Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/txrx.c

@@ -75,6 +75,7 @@ void ath10k_txrx_tx_unref(struct ath10k_htt *htt,
 	ath10k_report_offchan_tx(htt->ar, msdu);
 
 	info = IEEE80211_SKB_CB(msdu);
+	memset(info, 0, sizeof(*info));
 
 	if (tx_done->discard) {
 		ieee80211_free_txskb(htt->ar->hw, msdu);