Update use of Linux tty api

Update use of Linux tty api

The following commit changed the api:

commit 05c7cd39907184328f48d3e7899f9cdd653ad336
Author: Jiri Slaby <jslaby@suse.cz>
Date:   Thu Jan 3 15:53:04 2013 +0100

    TTY: switch tty_insert_flip_string

Fixes the following build failures against 3.13:

  In file included from xr21v141x-lnx-3.5-pak/vizzini.c:39:0:
  include/linux/tty_flip.h:29:19: note: expected ‘struct tty_port *’ but argument
  is of type ‘struct tty_struct *’
   static inline int tty_insert_flip_string(struct tty_port *port,
                     ^
  xr21v141x-lnx-3.5-pak/vizzini.c:364:2: warning: passing argument 1 of
  ‘tty_flip_buffer_push’ from incompatible pointer type [enabled by default]
    tty_flip_buffer_push(tty);
    ^
  In file included from xr21v141x-lnx-3.5-pak/vizzini.c:39:0:
  include/linux/tty_flip.h:14:13: note: expected ‘struct tty_port *’ but argument
  is of type ‘struct tty_struct *’
   extern void tty_flip_buffer_push(struct tty_port *port);
               ^

Signed-off-by: Joel Stanley <joel@jms.id.au>