iio: imu: st_lsm6dsx: Set buffer sampling frequency for accelerometer only

In the Linux kernel, the following vulnerability has been resolved: iio: imu: st_lsm6dsx: Set buffer sampling frequency for accelerometer only The st_lsm6dsx_hwfifo_odr_store() function, which is called when userspace writes the buffer sampling frequency sysfs attribute, calls st_lsm6dsx_check_odr(), which accesses the odr_table array at index `sensor->id`; since this array is only 2 entries long, an access for any sensor type other than accelerometer or gyroscope is an out-of-bounds access. The motivation for being able to set a buffer frequency different from the sensor sampling frequency is to support use cases that need accurate event detection (which requires a high sampling frequency) while retrieving sensor data at low frequency. Since all the supported event types are generated from acceleration data only, do not create the buffer sampling frequency attribute for sensor types other than the accelerometer.