Input: applespi - drop redundant input->dev.parent assignment

devm_input_allocate_device() already initializes input->dev.parent to
the supplied parent device, so the explicit assignments in
applespi_register_touchpad_device() and applespi_probe() are redundant.
Remove them.

Reported-by: sashiko-bot@kernel.org
Assisted-by: LLM
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>