net: fec: Do a sanity check on the gpio number

Check whether the phy-reset GPIO is valid, prior to requesting it.

In the case a board does not provide a phy-reset GPIO, just returns immediately.

With such gpio validation in place, it is also safe to change from pr_debug to
dev_err in the case the gpio request fails.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec.c

@@ -1689,10 +1689,13 @@ static void fec_reset_phy(struct platform_device *pdev)
 		msec = 1;
 
 	phy_reset = of_get_named_gpio(np, "phy-reset-gpios", 0);
+	if (!gpio_is_valid(phy_reset))
+		return;
+
 	err = devm_gpio_request_one(&pdev->dev, phy_reset,
 				    GPIOF_OUT_INIT_LOW, "phy-reset");
 	if (err) {
-		pr_debug("FEC: failed to get gpio phy-reset: %d\n", err);
+		dev_err(&pdev->dev, "failed to get phy-reset-gpios: %d\n", err);
 		return;
 	}
 	msleep(msec);