staging: comedi: addi_apci_1710: remove COMEDI_SUBD_TTLIO define

This define exists in hwdrv_APCI1710.c, where it's actually used.
Remove the duplicate define.

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>