serial: 8250_bcm7271: 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/20221019091151.6692-7-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_bcm7271.c

@@ -425,9 +425,7 @@ static int brcmuart_tx_dma(struct uart_8250_port *p)
 
 	priv->dma.tx_err = 0;
 	memcpy(priv->tx_buf, &xmit->buf[xmit->tail], tx_size);
-	xmit->tail += tx_size;
-	xmit->tail &= UART_XMIT_SIZE - 1;
-	p->port.icount.tx += tx_size;
+	uart_xmit_advance(&p->port, tx_size);
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(&p->port);