Add missing get_icount field to two-port driver.
The two-port driver was not updated when switching to the new icount
interface in commit 
0bca1b913aff ("tty: Convert the USB drivers to the
new icount interface").
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 
        .set_termios            = edge_set_termios,
        .tiocmget               = edge_tiocmget,
        .tiocmset               = edge_tiocmset,
+       .get_icount             = edge_get_icount,
        .write                  = edge_write,
        .write_room             = edge_write_room,
        .chars_in_buffer        = edge_chars_in_buffer,