iio: pressure: bmp280: reorder local variables following reverse xmas tree

Reordered definitions of local variables following the reverse christmas
tree convention.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Angel Iglesias <ang.iglesiasg@gmail.com>
Link: https://lore.kernel.org/r/363a106afbfe30ce590b80b1494c8b3322870f8a.1663025017.git.ang.iglesiasg@gmail.com


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