xhci: dbgtty: fix device unregister: fixup

This fixup replaces tty_vhangup() call with call to
tty_port_tty_vhangup(). Both calls hangup tty device
synchronously however tty_port_tty_vhangup() increases
reference count during the hangup operation using
scoped_guard(tty_port_tty).

Cc: stable <[e-mail]>
Fixes: 1f73b8b56cf3 ("xhci: dbgtty: fix device unregister")
Signed-off-by: Łukasz Bartosik <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/xhci-dbgtty.c

···
 	 * Hang up the TTY. This wakes up any blocked
 	 * writers and causes subsequent writes to fail.
 	 */
-	tty_vhangup(port->port.tty);
+	tty_port_tty_vhangup(&port->port);
 
 	tty_unregister_device(dbc_tty_driver, port->minor);
 	xhci_dbc_tty_exit_port(port);