staging: comedi: addi_apci_1710: remove dma setup/free code

This driver does not use dma. Remove the code that sets up the
dma and allocates the buffers in the attach and the code that
frees the buffers in the detach.

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>