serial: Make ->set_termios() old ktermios const

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index eafada8..1938ba5 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -323,7 +323,7 @@ static void sunhv_shutdown(struct uart_port *port)
 
 /* port->lock is not held.  */
 static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
-			      struct ktermios *old)
+			      const struct ktermios *old)
 {
 	unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 	unsigned int quot = uart_get_divisor(port, baud);