of_get_child_by_name() will increase the refcount of 'ofpart_node',
so add of_node_put() after using it to avoid refcount leak.

Fixes: 9b78ef0c ("mtd: parsers: add support for Sercomm partitions")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220617014008.851583-1-yangyingliang@huawei.com