staging: comedi: usbduxfast: tidy up usbduxfastsub_unlink_InURBs()

Rename this function so it has namespace associated with the driver.

Remove the local variables 'j' and 'ret'. They are not used and the
function always returns '0'.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>