PCI: mediatek: Fix refcount leak in mtk_pcie_subsys_powerup()

PCI: mediatek: Fix refcount leak in mtk_pcie_subsys_powerup()

The of_find_compatible_node() function returns a node pointer with
refcount incremented, We should use of_node_put() on it when done
Add the missing of_node_put() to release the refcount.

Link: https://lore.kernel.org/r/20220309091953.5630-1-linmq006@gmail.com
Fixes: 87e8657ba99c ("PCI: mediatek: Add new method to get shared pcie-cfg base address")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>