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/riscom8.c b/drivers/char/riscom8.c
index 0a8d1e5..b02332a 100644
--- a/drivers/char/riscom8.c
+++ b/drivers/char/riscom8.c
@@ -909,6 +909,7 @@
 	if (error)
 		return error;
 
+	tty->driver_data = port;
 	return tty_port_open(&port->port, tty, filp);
 }