commit 5492bf3d upstream.

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 0bca1b91 ("tty: Convert the USB drivers to the
new icount interface").
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>