staging: comedi: usbduxfast: use comedi_to_usb_dev()
staging: comedi: usbduxfast: use comedi_to_usb_dev()

Use the helper function to get a usb_device pointer from a
comedi_device pointer. This removes the need for also getting
the usb_interface pointer in some cases.

Signed-off-by: H Hartley Sweeten <382ff55d8e07d1082d179e669636cd1552da4f36@visionengravers.com>
Cc Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs