net: sparx5: Add of_node_put() before goto

Fix following coccicheck warning:
./drivers/net/ethernet/microchip/sparx5/s4parx5_main.c:723:1-33: WARNING: Function
for_each_available_child_of_node should have of_node_put() before goto

Early exits from for_each_available_child_of_node should decrement the
node reference counter.
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/sparx5/sparx5_main.c

@@ -758,6 +758,7 @@ static int mchp_sparx5_probe(struct platform_device *pdev)
 			err = dev_err_probe(sparx5->dev, PTR_ERR(serdes),
 					    "port %u: missing serdes\n",
 					    portno);
+			of_node_put(portnp);
 			goto cleanup_config;
 		}
 		config->portno = portno;