serial: 8250_dma: no need to sync RX buffer

RX buffer is allocated from DMA coherent memory. Thus there is no need to call
DMA sync API for it.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_dma.c

@@ -54,9 +54,6 @@ static void __dma_rx_complete(void *param)
 	struct dma_tx_state	state;
 	int			count;
 
-	dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
-				dma->rx_size, DMA_FROM_DEVICE);
-
 	dma->rx_running = 0;
 	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
 
@@ -156,9 +153,6 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
 
 	dma->rx_cookie = dmaengine_submit(desc);
 
-	dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr,
-				   dma->rx_size, DMA_FROM_DEVICE);
-
 	dma_async_issue_pending(dma->rxchan);
 
 	return 0;