tty: Fix regressions in the char driver conversion

This forgot to update a field in the old char drivers. The fact nobody
has basically noticed (except one mxser user) rather suggests most of these
drivers could go into the bitbucket.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Dan Carpenter <error27@gmail.com>
Cc: Andreas Pretzsch <apr@cn-eng.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/char/istallion.c b/drivers/char/istallion.c
index 4cd6c52..4e395c9 100644
--- a/drivers/char/istallion.c
+++ b/drivers/char/istallion.c
@@ -827,6 +827,8 @@
 		return -ENODEV;
 	if (portp->devnr < 1)
 		return -ENODEV;
+
+	tty->driver_data = portp;
 	return tty_port_open(&portp->port, tty, filp);
 }