TTY: devpts, don't care about TTY in devpts_get_tty

The goal is to stop setting and using tty->driver_data in devpts code.
It should be used solely by the driver's code, pty in this case.

First, here we remove TTY from devpts_get_tty and rename it to
devpts_get_priv. Note we do not remove type safety, we just shift the
[implicit] (void *) cast one layer up.

index was unused in devpts_get_tty, so remove that from the prototype
too.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index a82b399..65f7671 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -547,7 +547,7 @@
 	struct tty_struct *tty;
 
 	mutex_lock(&devpts_mutex);
-	tty = devpts_get_tty(pts_inode, idx);
+	tty = devpts_get_priv(pts_inode);
 	mutex_unlock(&devpts_mutex);
 	/* Master must be open before slave */
 	if (!tty)