staging: comedi: amplc_dio200: no need to set hw_dev

The call to `comedi_set_hw_dev()` from `dio200_pci_common_attach()` is
now unnecessary since `dio200_pci_common_attach()` is now only called
from this driver's `attach_pci` hook `dio200_attach_pci()` and the
comedi core now calls `comedi_set_hw_dev()` before calling that.  Remove
the unnecessary call.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>