parport: Add comments for parport_register_dev_model()

In preparation to remove parport_register_device(), copy the comments
to parport_register_dev_model() and modify the parameters according to
what parport_register_dev_model() has.

Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lore.kernel.org/r/20200403134325.11523-9-sudipm.mukherjee@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>