ath9k: Fix memleak on TX DMA failure

The driver-specific region has to be freed in case
of a DMA mapping failure.

Cc: stable@kernel.org
Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -1572,8 +1572,9 @@ static int ath_tx_setup_buffer(struct ieee80211_hw *hw, struct ath_buf *bf,
 					   skb->len, DMA_TO_DEVICE);
 	if (unlikely(dma_mapping_error(sc->dev, bf->bf_dmacontext))) {
 		bf->bf_mpdu = NULL;
-		DPRINTF(sc, ATH_DBG_CONFIG,
-			"dma_mapping_error() on TX\n");
+		kfree(tx_info_priv);
+		tx_info->rate_driver_data[0] = NULL;
+		DPRINTF(sc, ATH_DBG_FATAL, "dma_mapping_error() on TX\n");
 		return -ENOMEM;
 	}