iio: accel: mma8452: use the correct logic to get mma8452_data

Summary

In the Linux kernel, the following vulnerability has been resolved: iio: accel: mma8452: use the correct logic to get mma8452_data The original logic to get mma8452_data is wrong, the *dev point to the device belong to iio_dev. we can't use this dev to find the correct i2c_client. The original logic happen to work because it finally use dev->driver_data to get iio_dev. Here use the API to_i2c_client() is wrong and make reader confuse. To correct the logic, it should be like this struct mma8452_data *data = iio_priv(dev_get_drvdata(dev)); But after commit 8b7651f25962 ("iio: iio_device_alloc(): Remove unnecessary self drvdata"), the upper logic also can't work. When try to show the avialable scale in userspace, will meet kernel dump, kernel handle NULL pointer dereference. So use dev_to_iio_dev() to correct the logic. Dual fixes tags as the second reflects when the bug was exposed, whilst the first reflects when the original bug was introduced.