iio: pressure: bmp280: Add preinit callback

Adds preinit callback to execute operations on probe before applying
initial configuration.

Signed-off-by: Angel Iglesias <ang.iglesiasg@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/fa9513ffad37a6a43b6d46df9d8319ccab6f5870.1676823250.git.ang.iglesiasg@gmail.com


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