staging: comedi: usbduxsigma: tidy up usbdux_getstatusinfo()

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

Move the function closer to its only caller and tidy it up a bit.

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>