staging: comedi: pcl818: kzalloc'ed memory does not need to be cleared

The private data is kzalloc'ed in the (*attach). There is no need to
initialize and the members to 0.

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>