iio: adc: fix the return value handle for platform_get_irq()

There is no possible for platform_get_irq() to return 0
and the return value of platform_get_irq() is more sensible
to show the error reason.

Signed-off-by: Ruan Jinjie <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/bcm_iproc_adc.c

···
 	}
 
 	adc_priv->irqno = platform_get_irq(pdev, 0);
-	if (adc_priv->irqno <= 0)
-		return -ENODEV;
+	if (adc_priv->irqno < 0)
+		return adc_priv->irqno;
 
 	ret = regmap_update_bits(adc_priv->regmap, IPROC_REGCTL2,
 				IPROC_ADC_AUXIN_SCAN_ENA, 0);

drivers/iio/adc/lpc32xx_adc.c

···
 	}
 
 	irq = platform_get_irq(pdev, 0);
-	if (irq <= 0)
-		return -ENXIO;
+	if (irq < 0)
+		return irq;
 
 	retval = devm_request_irq(&pdev->dev, irq, lpc32xx_adc_isr, 0,
 				  LPC32XXAD_NAME, st);

drivers/iio/adc/npcm_adc.c

···
 	info->adc_sample_hz = clk_get_rate(info->adc_clk) / ((div + 1) * 2);
 
 	irq = platform_get_irq(pdev, 0);
-	if (irq <= 0) {
-		ret = -EINVAL;
+	if (irq < 0) {
+		ret = irq;
 		goto err_disable_clk;
 	}
 

drivers/iio/adc/spear_adc.c

···
 	}
 
 	irq = platform_get_irq(pdev, 0);
-	if (irq <= 0) {
-		ret = -EINVAL;
+	if (irq < 0) {
+		ret = irq;
 		goto errout2;
 	}