usb: host: ohci-at91: fix request of irq for optional gpio

[ Upstream commit 325b9313ec3be56c8e2fe03f977fee19cec75820 ]

atmel,oc-gpio is optional. Request its irq only when atmel,oc is set
in device tree.

devm_gpiod_get_index_optional returns NULL if -ENOENT. Check its
return value for NULL before error, because it is more probable that
atmel,oc is not set.

This fixes the following errors on boards where atmel,oc is not set in
device tree:
[    0.960000] at91_ohci 500000.ohci: failed to request gpio "overcurrent" IRQ
[    0.960000] at91_ohci 500000.ohci: failed to request gpio "overcurrent" IRQ
[    0.970000] at91_ohci 500000.ohci: failed to request gpio "overcurrent" IRQ
Signed-off-by: NTudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: NNicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ohci-at91.c

@@ -551,6 +551,8 @@ static int ohci_hcd_at91_drv_probe(struct platform_device *pdev)
 		pdata->overcurrent_pin[i] =
 			devm_gpiod_get_index_optional(&pdev->dev, "atmel,oc",
 						      i, GPIOD_IN);
+		if (!pdata->overcurrent_pin[i])
+			continue;
 		if (IS_ERR(pdata->overcurrent_pin[i])) {
 			err = PTR_ERR(pdata->overcurrent_pin[i]);
 			dev_err(&pdev->dev, "unable to claim gpio \"overcurrent\": %d\n", err);