auxdisplay: ks0108: initialize local parport variable

The local variable ks0108_parport is used by other functions to write to
the parallel port. We missed initializing it when we converted the
driver to use new Parallel Port codes.

Fixes: 4edd70c1 ("auxdisplay: ks0108: use new parport device model")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>