iio: imu: bno055: fix OOB access of hw_xlate array

iio: imu: bno055: fix OOB access of hw_xlate array

Fix a potential out-of-bounds array access of the hw_xlate array in
bno055.c.

In bno055_get_regmask(), hw_xlate was iterated over the length of the
vals array instead of the length of the hw_xlate array. In the case of
bno055_gyr_scale, the vals array is larger than the hw_xlate array,
so this could result in an out-of-bounds access. In practice, this
shouldn't happen though because a match should always be found which
breaks out of the for loop before it iterates beyond the end of the
hw_xlate array.

By adding a new hw_xlate_len field to the bno055_sysfs_attr, we can be
sure we are iterating over the correct length.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507100510.rGt1YOOx-lkp@intel.com/
Fixes: 4aefe1c2bd0c ("iio: imu: add Bosch Sensortec BNO055 core driver")
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250709-iio-const-data-19-v2-1-fb3fc9191251@baylibre.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>