spi: spi-davinci: Fix direction in dma_map_single()

Commit 048177ce3b3962852fd34a7e04938959271c7e70 (spi: spi-davinci:
convert to DMA engine API) introduced a regression: dma_map_single() is called with direction DMA_FROM_DEVICE for rx and for tx.

---

@@ -608,7 +608,7 @@ static int davinci_spi_bufs(struct spi_d
 		else
 			buf = (void *)t->tx_buf;
 		t->tx_dma = dma_map_single(&spi->dev, buf,
-				t->len, DMA_FROM_DEVICE);
+				t->len, DMA_TO_DEVICE);
 		if (!t->tx_dma) {
 			ret = -EFAULT;
 			goto err_tx_map;

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Cc: [email protected] # v3.7.x+
will get this applied to the correct stable kernels.

I'm wearing the brown bag for this one so other than fixing the Cc: it looks good.