iio: adc: ad7173: Use device_for_each_child_node_scoped() to simplify error paths.

iio: adc: ad7173: Use device_for_each_child_node_scoped() to simplify error paths.

This loop definition automatically releases the fwnode_handle on early
exit such as the error cases seen here.  This reducing boilerplate and
the chance of a resource leak being introduced in future.

Cc: Dumitru Ceclan <mitrutzceclan@gmail.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240330190849.1321065-6-jic23@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>