iio: adc: ad4130: Use device_for_each_child_node_scoped() to simplify error paths.

iio: adc: ad4130: Use device_for_each_child_node_scoped() to simplify error paths.

This loop definition removes the need for manual releasing of the fwnode_handle
in early exit paths (here an error path) allow simplfication of the code
and reducing the chance of future modificiations not releasing
fwnode_handle correctly.

Cc: Cosmin Tanislav <demonsingur@gmail.com>
Cc: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240330190849.1321065-5-jic23@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>