pinctrl: mediatek: fix module autoloading

Add MODULE_DEVICE_TABLE(), so the module could be properly autoloaded
based on the alias from of_device_id table.  Pin controllers are
considered core components, so usually they are built-in, however these
can be built and used as modules on some generic kernel.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Message-ID: <20240411064614.7409-2-krzk@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>