tty: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Acked-by: Timur Tabi <timur@tabi.org>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/fsl_lpuart.c

@@ -257,7 +257,7 @@ struct lpuart_port {
 	struct timer_list	lpuart_timer;
 };
 
-static struct of_device_id lpuart_dt_ids[] = {
+static const struct of_device_id lpuart_dt_ids[] = {
 	{
 		.compatible = "fsl,vf610-lpuart",
 	},