iio: potentiostat: lmp91000: Fix alignment of buffer in iio_push_to_buffers_with_time...

iio: potentiostat: lmp91000: Fix alignment of buffer in iio_push_to_buffers_with_timestamp()

[ Upstream commit 8979b67ec61abc232636400ee8c758a16a73c95f ]

Add __aligned(8) to ensure the buffer passed to
iio_push_to_buffers_with_timestamp() is suitable for the naturally
aligned timestamp that will be inserted.

Here structure is not used, because this buffer is also used
elsewhere in the driver.

Fixes: 67e17300dc1d ("iio: potentiostat: add LMP91000 support")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Matt Ranostay <matt.ranostay@konsulko.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Link: https://lore.kernel.org/r/20210501171352.512953-8-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>