Blackfin Serial Driver: fix missing new lines when under load

Add a SSYNC() into bfin_serial_dma_tx_chars() to ensure DMA registers are
written with new data otherwise we might miss a byte or two when the
system is under load.  PIO mode is OK though.
Signed-off-by: NGraf Yang <graf.yang@analog.com>
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NBryan Wu <cooloney@kernel.org>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/serial/bfin_5xx.c

@@ -415,6 +415,7 @@ static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart)
 	set_dma_start_addr(uart->tx_dma_channel, (unsigned long)(xmit->buf+xmit->tail));
 	set_dma_x_count(uart->tx_dma_channel, uart->tx_count);
 	set_dma_x_modify(uart->tx_dma_channel, 1);
+	SSYNC();
 	enable_dma(uart->tx_dma_channel);
 
 	UART_SET_IER(uart, ETBEI);