extcon: max14577: fix handling return value of regmap_irq_get_virq

The function can return negative values, so its result should
be assigned to signed variable.

The problem has been detected using proposed semantic patch
scripts/coccinelle/tests/assign_signed_to_unsigned.cocci [1].

[1]: http://permalink.gmane.org/gmane.linux.kernel/2046107

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

drivers/extcon/extcon-max14577.c

@@ -692,7 +692,7 @@ static int max14577_muic_probe(struct platform_device *pdev)
 	/* Support irq domain for max14577 MUIC device */
 	for (i = 0; i < info->muic_irqs_num; i++) {
 		struct max14577_muic_irq *muic_irq = &info->muic_irqs[i];
-		unsigned int virq = 0;
+		int virq = 0;
 
 		virq = regmap_irq_get_virq(max14577->irq_data, muic_irq->irq);
 		if (virq <= 0)