pmdomain: imx: Fix reference count leak in imx_gpc_probe()

of_get_child_by_name() returns a node pointer with refcount incremented.
Use the __free() attribute to manage the pgc_node reference, ensuring
automatic of_node_put() cleanup when pgc_node goes out of scope.

This eliminates the need for explicit error handling paths and avoids
reference count leaks.

Fixes: 721cabf ("soc: imx: move PGC handling to a new GPC driver")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: ISCAS-Vulab

drivers/pmdomain/imx/gpc.c

@@ -402,13 +402,12 @@ static int imx_gpc_old_dt_init(struct device *dev, struct regmap *regmap,
 static int imx_gpc_probe(struct platform_device *pdev)
 {
 	const struct imx_gpc_dt_data *of_id_data = device_get_match_data(&pdev->dev);
-	struct device_node *pgc_node;
+	struct device_node *pgc_node __free(device_node)
+		= of_get_child_by_name(pdev->dev.of_node, "pgc");
 	struct regmap *regmap;
 	void __iomem *base;
 	int ret;
 
-	pgc_node = of_get_child_by_name(pdev->dev.of_node, "pgc");
-
 	/* bail out if DT too old and doesn't provide the necessary info */
 	if (!of_property_present(pdev->dev.of_node, "#power-domain-cells") &&
 	    !pgc_node)