serial: samsung: fix maxburst parameter for DMA transactions

The best granularity of residue that DMA engine can report is in the BURST
units, so the serial driver must use MAXBURST = 1 and DMA_SLAVE_BUSWIDTH_1_BYTE
if it relies on exact number of bytes transferred by DMA engine.

Fixes: 62c37eedb74c ("serial: samsung: add dma reqest/release functions")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/samsung.c

@@ -862,15 +862,12 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
 	dma->rx_conf.direction		= DMA_DEV_TO_MEM;
 	dma->rx_conf.src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
 	dma->rx_conf.src_addr		= p->port.mapbase + S3C2410_URXH;
-	dma->rx_conf.src_maxburst	= 16;
+	dma->rx_conf.src_maxburst	= 1;
 
 	dma->tx_conf.direction		= DMA_MEM_TO_DEV;
 	dma->tx_conf.dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
 	dma->tx_conf.dst_addr		= p->port.mapbase + S3C2410_UTXH;
-	if (dma_get_cache_alignment() >= 16)
-		dma->tx_conf.dst_maxburst = 16;
-	else
-		dma->tx_conf.dst_maxburst = 1;
+	dma->tx_conf.dst_maxburst	= 1;
 
 	dma->rx_chan = dma_request_chan(p->port.dev, "rx");