iio: magn: bmc150: Fix buffer alignment in iio_push_to_buffers_with_timestamp()

To make code more readable, use a structure to express the channel
layout and ensure the timestamp is 8 byte aligned.

Found during an audit of all calls of uses of
iio_push_to_buffers_with_timestamp()

Fixes: c91746a2 ("iio: magn: Add support for BMC150 magnetometer")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-17-jic23@kernel.org

drivers/iio/magnetometer/bmc150_magn.c

@@ -138,8 +138,11 @@ struct bmc150_magn_data {
 	struct regmap *regmap;
 	struct regulator_bulk_data regulators[2];
 	struct iio_mount_matrix orientation;
-	/* 4 x 32 bits for x, y z, 4 bytes align, 64 bits timestamp */
-	s32 buffer[6];
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		s32 chans[3];
+		s64 timestamp __aligned(8);
+	} scan;
 	struct iio_trigger *dready_trig;
 	bool dready_trigger_on;
 	int max_odr;
@@ -672,11 +675,11 @@ static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
 	int ret;
 
 	mutex_lock(&data->mutex);
-	ret = bmc150_magn_read_xyz(data, data->buffer);
+	ret = bmc150_magn_read_xyz(data, data->scan.chans);
 	if (ret < 0)
 		goto err;
 
-	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 					   pf->timestamp);
 
 err: