don't check platform_get_irq's return value against zero

platform_get_irq returns -ENXIO on failure, so !int_irq was probably
always true.  Better use (int)int_irq <= 0.  Note that a return value of
zero is still handled as error even though this could mean irq0.

This is a followup to 305b3228 that
changed the return value of platform_get_irq from 0 to -ENXIO on error.
Acked-by: NHans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NHans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>

arch/avr32/mach-at32ap/extint.c

@@ -191,7 +191,7 @@ static int __init eic_probe(struct platform_device *pdev)
 
 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	int_irq = platform_get_irq(pdev, 0);
-	if (!regs || !int_irq) {
+	if (!regs || (int)int_irq <= 0) {
 		dev_dbg(&pdev->dev, "missing regs and/or irq resource\n");
 		return -ENXIO;
 	}