ASoC: mediatek: mt8192-mt6359: fix device_node leak

The of_parse_phandle() document:
    >>> Use of_node_put() on it when done.

The driver didn't call of_node_put().  Fixes the leak.

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20211214040028.2992627-1-tzungbi@google.com
Signed-off-by: Mark Brown <broonie@kernel.org>