Staging: comedi: drivers: ni_6527: fixup checkpatch.pl warnings

This patch fixes all warnings as issued by checkpatch.pl.
Note that I had to modify some of the logging messages to make that possible.

Signed-off-by: Klaas van Gend <klaas.van.gend@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>