staging: comedi: dt9812: move the usb framework functions to EOF

In preparation of converting this manually attached comedi driver
into an auto attached comedi usb driver, move the usb framework
functions to the end of the file.
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>