staging:iio:lpc32xx_adc: Fix IRQ check

The test in the lpc32xx_adc driver which checks whether the IRQ number returned
by platform_get_irq() has multiple problems. It accepts 0 even though this is an
invalid IRQ. It also rejects IRQ numbers that are larger or equal than NR_IRQS.
First of all drivers should never need to reference NR_IRQS and secondly with
CONFIG_SPARSE_IRQ NR_IRQS is not the upper limit, so the check might reject
valid IRQ numbers. This patch modifies the check to only test against less or
equal to 0.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Roland Stigge <stigge@antcom.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/lpc32xx_adc.c

@@ -160,7 +160,7 @@ static int lpc32xx_adc_probe(struct platform_device *pdev)
 	}
 
 	irq = platform_get_irq(pdev, 0);
-	if ((irq < 0) || (irq >= NR_IRQS)) {
+	if (irq <= 0) {
 		dev_err(&pdev->dev, "failed getting interrupt resource\n");
 		return -EINVAL;
 	}