USB: serial: omninet: fix reference leaks at open

commit 30572418 upstream.

This driver needlessly took another reference to the tty on open, a
reference which was then never released on close. This lead to not just
a leak of the tty, but also a driver reference leak that prevented the
driver from being unloaded after a port had once been opened.

Fixes: 4a90f09b ("tty: usb-serial krefs")
Signed-off-by: Johan Hovold <johan@kernel.org>
[bwh: Backported to 3.2:
 - The 'serial' variable is still needed for other initialisation
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/serial/omninet.c

@@ -171,14 +171,10 @@ static int omninet_attach(struct usb_serial *serial)
 static int omninet_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
 	struct usb_serial	*serial = port->serial;
-	struct usb_serial_port	*wport;
 	int			result = 0;
 
 	dbg("%s - port %d", __func__, port->number);
 
-	wport = serial->port[1];
-	tty_port_tty_set(&wport->port, tty);
-
 	/* Start reading from the device */
 	usb_fill_bulk_urb(port->read_urb, serial->dev,
 			usb_rcvbulkpipe(serial->dev,