staging: comedi: addi_apci_2200: remove devpriv allocation

The 'devpriv' is not used in this driver. Remove it's allocation
in the auto_attach and the check for it 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>