Staging: comedi: gsc_hpdi: style fixes printk

Style cleanup in staging based on Greg's tutorial / checkpatch
Add printk KERN_ facility level (KERN_WARNING seemed appropriate for all)

Signed-off-by: Dirk Hohndel <hohndel@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>