staging: comedi: aio_aio12_8: fix i/o region size

This board has jumpers to set the board base address. These
jumpers are marked A5 through A9 and A5 is the least significant
bit of the address. This makes the address reqion for the board
32 bytes not 24.

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