USB: io_ti: fix sysfs-attribute creation

Make sure port data is initialised before creating sysfs attributes to
avoid a race.

A recent patch ("USB: io_ti: fix port-data memory leak") got the
sysfs-attribute creation and port-data initialisation ordering wrong.

Cc: <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>