iio: adis_buffer: do not return ints in irq handlers

On an IRQ handler we should not return normal error codes as 'irqreturn_t'
is expected.

Not necessarily stable material as the old check cannot fail, so it's a bug
we can not hit.

Fixes: ccd2b52f ("staging:iio: Add common ADIS library")
Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210422101911.135630-2-nuno.sa@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/adis_buffer.c

@@ -129,9 +129,6 @@ static irqreturn_t adis_trigger_handler(int irq, void *p)
 	struct adis *adis = iio_device_get_drvdata(indio_dev);
 	int ret;
 
-	if (!adis->buffer)
-		return -ENOMEM;
-
 	if (adis->data->has_paging) {
 		mutex_lock(&adis->state_lock);
 		if (adis->current_page != 0) {