gpio: ucb1400: Remove platform setup and teardown support

There is no user of these callbacks. The motivation for this change is
to stop returning an error code from the remove callback.

This is a preparation for making platform remove callbacks return void.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>