Modify ppdev driver to use the new parallel port device model.

Initially submitted and committed as:
e7223f18 ("ppdev: use new parport device model")

But due to some regression it was reverted by:
1701f680 ("Revert "ppdev: use new parport device model"")

Now that the original source of regression is fixed by:
bbca503b ("parport: use subsys_initcall") we can again modify ppdev
to use device model.
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>