HSI: nokia-modem: fix error handling of irq_of_parse_and_map

Return value of irq_of_parse_and_map() is unsigned int, with 0
indicating failure, so testing for negative result never works.
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/hsi/clients/nokia-modem.c

@@ -164,9 +164,9 @@ static int nokia_modem_probe(struct device *dev)
 	dev_set_drvdata(dev, modem);
 
 	irq = irq_of_parse_and_map(np, 0);
-	if (irq < 0) {
+	if (!irq) {
 		dev_err(dev, "Invalid rst_ind interrupt (%d)\n", irq);
-		return irq;
+		return -EINVAL;
 	}
 	modem->nokia_modem_rst_ind_irq = irq;
 	pflags = irq_get_trigger_type(irq);