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/[e-mail]
Fixes: 87e8657ba99c ("PCI: mediatek: Add new method to get shared pcie-cfg base address")
Signed-off-by: Miaoqian Lin <[e-mail]>
Signed-off-by: Lorenzo Pieralisi <[e-mail]>
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Reviewed-by: Miles Chen <[e-mail]>
Acked-by: Rob Herring <[e-mail]>

drivers/pci/controller/pcie-mediatek.c

···
 					   "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);
 	}