iio:ad7266: Mark transfer buffer as __be16

Fixes the following warnings from sparse:
drivers/iio/adc/ad7266.c:140:16: warning: cast to restricted __be16
drivers/iio/adc/ad7266.c:140:16: warning: cast to restricted __be16
drivers/iio/adc/ad7266.c:140:16: warning: cast to restricted __be16
drivers/iio/adc/ad7266.c:140:16: warning: cast to restricted __be16

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/ad7266.c

···
 	 * The buffer needs to be large enough to hold two samples (4 bytes) and
 	 * the naturally aligned timestamp (8 bytes).
 	 */
-	uint8_t data[ALIGN(4, sizeof(s64)) + sizeof(s64)] ____cacheline_aligned;
+	struct {
+		__be16 sample[2];
+		s64 timestamp;
+	} data ____cacheline_aligned;
 };
 
 static int ad7266_wakeup(struct ad7266_state *st)
 {
 	/* Any read with >= 2 bytes will wake the device */
-	return spi_read(st->spi, st->data, 2);
+	return spi_read(st->spi, &st->data.sample[0], 2);
 }
 
 static int ad7266_powerdown(struct ad7266_state *st)
 {
 	/* Any read with < 2 bytes will powerdown the device */
-	return spi_read(st->spi, st->data, 1);
+	return spi_read(st->spi, &st->data.sample[0], 1);
 }
 
 static int ad7266_preenable(struct iio_dev *indio_dev)
···
 	struct ad7266_state *st = iio_priv(indio_dev);
 	int ret;
 
-	ret = spi_read(st->spi, st->data, 4);
+	ret = spi_read(st->spi, st->data.sample, 4);
 	if (ret == 0) {
-		iio_push_to_buffers_with_timestamp(indio_dev, st->data,
+		iio_push_to_buffers_with_timestamp(indio_dev, &st->data,
 			    pf->timestamp);
 	}
 
···
 	ad7266_select_input(st, address);
 
 	ret = spi_sync(st->spi, &st->single_msg);
-	*val = be16_to_cpu(st->data[address % 2]);
+	*val = be16_to_cpu(st->data.sample[address % 2]);
 
 	return ret;
 }
···
 	ad7266_init_channels(indio_dev);
 
 	/* wakeup */
-	st->single_xfer[0].rx_buf = &st->data;
+	st->single_xfer[0].rx_buf = &st->data.sample[0];
 	st->single_xfer[0].len = 2;
 	st->single_xfer[0].cs_change = 1;
 	/* conversion */
-	st->single_xfer[1].rx_buf = &st->data;
+	st->single_xfer[1].rx_buf = st->data.sample;
 	st->single_xfer[1].len = 4;
 	st->single_xfer[1].cs_change = 1;
 	/* powerdown */
-	st->single_xfer[2].tx_buf = &st->data;
+	st->single_xfer[2].tx_buf = &st->data.sample[0];
 	st->single_xfer[2].len = 1;
 
 	spi_message_init(&st->single_msg);