staging: comedi: ni_labpc_isadma: use comedi_isdma module

The labpc driver has already had the depends on ISA_DMA_API limitation removed
by moving all the DMA support code into the labpc_isadma module.

For aesthetics, use the comedi_isadma module to provide the actual ISA DMA
support.

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>