iio: imu: bmi323: Make the local structures static

Make the local structures static within their respective driver files.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311070530.qKhLTz1Y-lkp@intel.com/


Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>
Link: https://lore.kernel.org/r/20231108035831.5889-1-jagathjog1996@gmail.com


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