staging: comedi: vmk80xx: remove VMK80XX_SUBD_* enum

These enum values are only used in the initialization of the
comedi_subdevices. They don't help make the code any clearer
so just remove them.

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>