gpio: pl061: Warn when IRQ line has not been configured

Existing (irq < 0) condition is always false because adev->irq has unsigned
type and contains 0 in case of failed irq_of_parse_and_map(). Up to now all
the mapping errors were silently ignored.

Seems that repairing this check would be backwards-incompatible and might
break the probe() for the implementations without IRQ support. Therefore
warn the user instead.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/gpio/gpio-pl061.c

@@ -326,10 +326,8 @@ static int pl061_probe(struct amba_device *adev, const struct amba_id *id)
 
 	writeb(0, pl061->base + GPIOIE); /* disable irqs */
 	irq = adev->irq[0];
-	if (irq < 0) {
-		dev_err(&adev->dev, "invalid IRQ\n");
-		return -ENODEV;
-	}
+	if (!irq)
+		dev_warn(&adev->dev, "IRQ support disabled\n");
 	pl061->parent_irq = irq;
 
 	girq = &pl061->gc.irq;