staging: comedi: usbduxfast: tidy up usbduxfast_attach_common()

Remove the unnecessary comments and tidy up the whitespace in
this function.

Also, remove the dev_info() at the end. It's just added noise.

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>