TTY: ircomm, use flags from tty_port

Switch to tty_port->flags. And while at it, remove redefined flags for
them.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>