serial: rda: Use uart_xmit_advance()

Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-28-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/rda-uart.c

@@ -353,8 +353,7 @@ static void rda_uart_send_chars(struct uart_port *port)
 
 		ch = xmit->buf[xmit->tail];
 		rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
+		uart_xmit_advance(port, 1);
 	}
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)