ath10k: fix dma_mapping_error() handling

The function returns 1 when DMA mapping fails. The
driver would return bogus values and could
possibly confuse itself if DMA failed.

Fixes: 767d34fc67af ("ath10k: remove DMA mapping wrappers")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
index 704bb5e..43aa5e2 100644
--- a/drivers/net/wireless/ath/ath10k/htt_tx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
@@ -442,8 +442,10 @@
 	skb_cb->paddr = dma_map_single(dev, msdu->data, msdu->len,
 				       DMA_TO_DEVICE);
 	res = dma_mapping_error(dev, skb_cb->paddr);
-	if (res)
+	if (res) {
+		res = -EIO;
 		goto err_free_txdesc;
+	}
 
 	skb_put(txdesc, len);
 	cmd = (struct htt_cmd *)txdesc->data;
@@ -533,8 +535,10 @@
 	skb_cb->paddr = dma_map_single(dev, msdu->data, msdu->len,
 				       DMA_TO_DEVICE);
 	res = dma_mapping_error(dev, skb_cb->paddr);
-	if (res)
+	if (res) {
+		res = -EIO;
 		goto err_free_txbuf;
+	}
 
 	switch (skb_cb->txmode) {
 	case ATH10K_HW_TXRX_RAW: