net: ethernet: mediatek: add missing of_node_put() in mtk_sgmii_init()

The node pointer returned by of_parse_phandle() with refcount incremented,
so add of_node_put() after using it in mtk_sgmii_init().

Fixes: 9ffee4a8 ("net: ethernet: mediatek: Extend SGMII related functions")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20220428062543.64883-1-yangyingliang@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mediatek/mtk_sgmii.c

@@ -26,6 +26,7 @@ int mtk_sgmii_init(struct mtk_sgmii *ss, struct device_node *r, u32 ana_rgc3)
 			break;
 
 		ss->regmap[i] = syscon_node_to_regmap(np);
+		of_node_put(np);
 		if (IS_ERR(ss->regmap[i]))
 			return PTR_ERR(ss->regmap[i]);
 	}