Staging: comedi: remove usb wrappers

The usb wrapper macros are no longer needed, as all of
the comedi drivers using them have been converted to
use the "native" USB core calls.

Cc: Anders Blomdell <anders.blomdell@control.lth.se>
Cc: David Schleef <ds@schleef.org>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>