Fix the following coccicheck warning:

drivers/comedi/drivers.c:857:12-13: WARNING opportunity for min().

min() macro is defined in include/linux/minmax.h. It avoids multiple
evaluations of the arguments when non-constant and performs strict
type-checking.
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Link: https://lore.kernel.org/r/20220513071608.49047-1-guozhengkui@vivo.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>