sfp: Fix error handing in sfp_probe()

gpiod_to_irq() never return 0, but returns negative in
case of error, check it and set gpio_irq to 0.

Fixes: 73970055 ("sfp: add SFP module support")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20201031031053.25264-1-yuehaibing@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/sfp.c

@@ -2389,7 +2389,8 @@ static int sfp_probe(struct platform_device *pdev)
 			continue;
 
 		sfp->gpio_irq[i] = gpiod_to_irq(sfp->gpio[i]);
-		if (!sfp->gpio_irq[i]) {
+		if (sfp->gpio_irq[i] < 0) {
+			sfp->gpio_irq[i] = 0;
 			sfp->need_poll = true;
 			continue;
 		}