iio: adc: ti-ads1015: use device_for_each_child_node_scoped()

iio: adc: ti-ads1015: use device_for_each_child_node_scoped()

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

Co-developed-by: Luiza Soezima <lbrsoezima@usp.br>
Signed-off-by: Luiza Soezima <lbrsoezima@usp.br>
Co-developed-by: Sabrina Araujo <sabrinaaraujo@usp.br>
Signed-off-by: Sabrina Araujo <sabrinaaraujo@usp.br>
Signed-off-by: Lincoln Yuji <lincolnyuji@usp.br>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Link: https://lore.kernel.org/r/20240429132233.6266-1-lincolnyuji@usp.br
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>