iio: chemical: ams-iaq-core: clean up codestyle warning

This fixes a checkpatch warning by changing the struct attribute from __attribute__((__packed__)) to __packed.

Signed-off-by: Bruna Bispo <blbispo1@gmail.com>
Link: https://lore.kernel.org/r/20240528143816.13409-1-blbispo1@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>