staging: comedi: addi_apci_1564: board has 32 digital inputs

This board always has 32 digital inputs. Remove the test when
initializing the subdevice.

Also, since this board is the only one supported by this driver,
remove the boardinfo about the digital inputs and just use the
data directly in the subdevice init.

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