serial: sh-sci: Take into account sampling rate for max baud rate

The maximum baud rate depends on the sampling rate.
HSCIF has a variable sampling rate and sets s->sampling_rate to zero,
hence use the minimum sampling rate of 8.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sh-sci.c

@@ -1975,7 +1975,10 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 	 * that the previous boot loader has enabled required clocks and
 	 * setup the baud rate generator hardware for us already.
 	 */
-	max_baud = port->uartclk ? port->uartclk / 16 : 115200;
+	if (port->uartclk)
+		max_baud = port->uartclk / max(s->sampling_rate, 8U);
+	else
+		max_baud = 115200;
 
 	baud = uart_get_baud_rate(port, termios, old, 0, max_baud);
 	if (likely(baud && port->uartclk))