TTY: mark tty_get_device call with the proper const values

Michał's previous patch missed this tty check to fix up the
class_find_device() arguments.
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Cc: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_io.c

@@ -2906,9 +2906,9 @@ void do_SAK(struct tty_struct *tty)
 
 EXPORT_SYMBOL(do_SAK);
 
-static int dev_match_devt(struct device *dev, void *data)
+static int dev_match_devt(struct device *dev, const void *data)
 {
-	dev_t *devt = data;
+	const dev_t *devt = data;
 	return dev->devt == *devt;
 }