staging: comedi: daqboard2000: use type 'u16' for CPLD data and status

The CPLD status and data registers used to load firmware are 16 bits
wide.  Use the type `u16` to represent data and status values instead of
`int`.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>