iio: imu: st_lsm6dsx: Fix mismatched comments

odr to odr_table
gain to fs_table

'gain' is actually in 'st_lsm6dsx_fs' structure of 'fs_table'

Signed-off-by: JieunKim <jieun.kim4758@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>