Staging: comedi: newer gcc warning fixes

Fix GCC warning in call to request_module(): "format not a string
literal and no format arguments".

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