tty: cpm_uart, use port->flags instead of low_latency

This is the only in-kernel user of tty_port::low_latency. Switch this
last one to test uport->flags directly as tty_port::low_latency is going
away in the next patch.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-10-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/cpm_uart/cpm_uart_core.c

@@ -499,8 +499,7 @@ static void cpm_uart_set_termios(struct uart_port *port,
 	pr_debug("CPM uart[%d]:set_termios\n", port->line);
 
 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
-	if (baud < HW_BUF_SPD_THRESHOLD ||
-	    (pinfo->port.state && pinfo->port.state->port.low_latency))
+	if (baud < HW_BUF_SPD_THRESHOLD || port->flags & UPF_LOW_LATENCY)
 		pinfo->rx_fifosize = 1;
 	else
 		pinfo->rx_fifosize = RX_BUF_SIZE;