platform: arm64: huawei-gaokun-ec: fix OF node leak

Make sure to drop the OF node reference taken when creating the Gaokun
auxiliary devices when the devices are later released.

Fixes: 7636f090 ("platform: arm64: add Huawei Matebook E Go EC driver")
Cc: Pengyu Luo <mitltlatltl@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Pengyu Luo <mitltlatltl@gmail.com>
Link: https://lore.kernel.org/r/20250708085358.15657-1-johan@kernel.org


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>