staging: comedi: addi-data: remove unused 'i_NbrTTLChannel' boardinfo

None of the addi-data drivers that still use the "common" code have
ttl digital i/o. Remove the unnecessary boardinfo as well as the
subdevice initialization code.

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>