generic-adc-battery: Fix checking return value of request_any_context_irq

On failure, request_any_context_irq() returns a negative value. On
success, it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>

drivers/power/generic-adc-battery.c

@@ -327,7 +327,7 @@ static int __devinit gab_probe(struct platform_device *pdev)
 		ret = request_any_context_irq(irq, gab_charged,
 				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 				"battery charged", adc_bat);
-		if (ret)
+		if (ret < 0)
 			goto err_gpio;
 	}