serial: clps711x: 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/20221019091151.6692-13-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/clps711x.c

@@ -166,8 +166,7 @@ static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
 		u32 sysflg = 0;
 
 		writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
+		uart_xmit_advance(port, 1);
 
 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 		if (sysflg & SYSFLG_UTXFF)