nozomi: Add tty_port usage

The Nozomi tty handling is very broken on the open/close side (See
http://bugzilla.kernel.org/show_bug.cgi?id=13024

 for one example). In
particular it marks the tty as closed on the first close() not on the last.

Most of the logic is pretty solid except for the open/close path so switch
to the tty_port helpers and let them do all the heavy lifting. This is also
fixes all the POSIX behaviour violations in the open/close paths.

Begin by adding the tty port usage

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>