STAGING: COMEDI: Remove unnecessary typecast of c90 int constant

This patch removes unnecessary typecast of c90 int constant.

Signed-off-by: Pablo G. Gallardo <pggllrd@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>