Staging: comedi: fixed warning shown by checkpatch tool on cb_das16_cs.c file

This is a patch to fix the warnings shown by checkpatch tool on
file cb_das16_cs.c

Signed-off-by: Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>