iio: health: afe4403: Use devm IIO helpers

Use a device lifecycle managed IIO helper functions. This helps prevent
mistakes like unregistering and freeing out of order in cleanup functions
and forgetting to unregister and free on error paths.

Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20240123140918.215818-2-afd@ti.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>