gpio: gpio-tegra186: remove empty remove hook

The tegra186_gpio_remove hook simply does a return 0.
Not defining it yields pretty much the same result.
So, this can be removed.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>