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: 87e8657ba9 ("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>

drivers/pci/controller/pcie-mediatek.c

@@ -1008,6 +1008,7 @@ static int mtk_pcie_subsys_powerup(struct mtk_pcie *pcie)
 					   "mediatek,generic-pciecfg");
 	if (cfg_node) {
 		pcie->cfg = syscon_node_to_regmap(cfg_node);
+		of_node_put(cfg_node);
 		if (IS_ERR(pcie->cfg))
 			return PTR_ERR(pcie->cfg);
 	}