staging: comedi: addi-data: remove unused vars from boardinfo

Due to the on-going cleanup of the addi-data drivers, the boardinfo
used in the "common" code has a number of variables that are not
used. Remove the cruft.

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