iio: accel: adxl345: convert probe to device-managed functions

iio: accel: adxl345: convert probe to device-managed functions

This driver has two parts, one for i2c and one for spi, since the chip can
operate with both wire protocols.

The core file has a common adxl345_core_remove() function which puts the
chip into a powerdown state. This can be implemented with a
devm_add_action_or_reset() hook.

Doing that means we can register the IIO device with
devm_iio_device_register() and get rid of the adxl345_core_remove()
function.

The dev_set_drvdata() call can be removed as there is no other user of this
private data anymore.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210624080441.8710-1-aardelean@deviqon.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>