ata: pata_parport: switch to dynamic root device

ata: pata_parport: switch to dynamic root device

Driver core expects devices to be dynamically allocated and will, for
example, complain loudly when no release function has been provided.

Use root_device_register() to allocate and register the root device
instead of open coding using a static device.

Note that this also fixes a reference leak in the unlikely event that
device_register() ever fails.

Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Niklas Cassel <cassel@kernel.org>