ath9k: fix inconsistent indenting on return statement

minor change, indenting is one tab out.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>

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

@@ -2915,7 +2915,7 @@ int ath9k_tx99_send(struct ath_softc *sc, struct sk_buff *skb,
 		if (skb_headroom(skb) < padsize) {
 			ath_dbg(common, XMIT,
 				"tx99 padding failed\n");
-		return -EINVAL;
+			return -EINVAL;
 		}
 
 		skb_push(skb, padsize);