tty/hvc_opal: 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/hvc/hvc_opal.c

@@ -41,7 +41,7 @@
 
 static const char hvc_opal_name[] = "hvc_opal";
 
-static struct of_device_id hvc_opal_match[] = {
+static const struct of_device_id hvc_opal_match[] = {
 	{ .name = "serial", .compatible = "ibm,opal-console-raw" },
 	{ .name = "serial", .compatible = "ibm,opal-console-hvsi" },
 	{ },