staging: comedi: s526: remove unused variables in the private data

The 'data' and 'pci_dev' variables in the private data are not used.
They appear to be cut-and-paste from the skel driver. 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>