carl9170: fix carl9170_tx_prepare typo

commit: "carl9170: revamp carl9170_tx_prepare"
introduced a peculiar bug that would only show
up if the the module parameter noht is set to 1.

Then all outbound voice, video and background
frames would each invoke a (bogus) RTS/CTS
handshake.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/carl9170/tx.c

@@ -810,7 +810,7 @@ static int carl9170_tx_prepare(struct ar9170 *ar, struct sk_buff *skb)
 
 	mac_tmp = cpu_to_le16(AR9170_TX_MAC_HW_DURATION |
 			      AR9170_TX_MAC_BACKOFF);
-	mac_tmp |= cpu_to_le16((hw_queue << AR9170_TX_MAC_QOS_S) &&
+	mac_tmp |= cpu_to_le16((hw_queue << AR9170_TX_MAC_QOS_S) &
 			       AR9170_TX_MAC_QOS);
 
 	no_ack = !!(info->flags & IEEE80211_TX_CTL_NO_ACK);