serial: 8250_dma: Export serial8250_rx_dma_flush()

Export serial8250_rx_dma_flush() for use by SOC UART drivers.
Signed-off-by: Chuah, Kim Tatt <kim.tatt.chuah@intel.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -145,6 +145,7 @@ void serial8250_rx_dma_flush(struct uart_8250_port *p)
 		dmaengine_terminate_all(dma->rxchan);
 	}
 }
+EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
 
 int serial8250_request_dma(struct uart_8250_port *p)
 {