iio: adc: vf610: fix the adc register read fail issue

Read the register only when the adc register address is 4 byte aligned.
(rather than the other way around).
Signed-off-by: NHaibo Chen <haibo.chen@freescale.com>
Signed-off-by: NFugang Duan <B38611@freescale.com>
Cc: <Stable.vger.kernel.org>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/adc/vf610_adc.c

@@ -635,7 +635,7 @@ static int vf610_adc_reg_access(struct iio_dev *indio_dev,
 	struct vf610_adc *info = iio_priv(indio_dev);
 
 	if ((readval == NULL) ||
-		(!(reg % 4) || (reg > VF610_REG_ADC_PCTL)))
+		((reg % 4) || (reg > VF610_REG_ADC_PCTL)))
 		return -EINVAL;
 
 	*readval = readl(info->regs + reg);