staging: comedi: me4000: remove struct me4000_dio_info

The me4000_dio_info in the boardinfo struct is used to indicate
the number of 8 bit dio ports the the board has. Add a 'dio_nchan'
field to struct me4000_board and remove the struct me4000_dio_info.
The 'dio_nchan' value can then be used directly in the attach of
the board when setting the subdevice number of channels.

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>