staging: comedi: amplc_dio200.h: remove 'mainsize' from boardinfo

This member of the boardinfo is not used by the drivers. Remove it.

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>