[media] atmel-isi: Update error check for unsigned variables

Checking '< 0' for unsigned variables always returns false. For error
codes, use IS_ERR_VALUE() instead.
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/platform/soc_camera/atmel-isi.c

@@ -1021,7 +1021,7 @@ static int atmel_isi_probe(struct platform_device *pdev)
 	isi_writel(isi, ISI_CTRL, ISI_CTRL_DIS);
 
 	irq = platform_get_irq(pdev, 0);
-	if (irq < 0) {
+	if (IS_ERR_VALUE(irq)) {
 		ret = irq;
 		goto err_req_irq;
 	}