net: hns: hisilicon: hns_dsaf_mac: switch to scoped device_for_each_child_node()

Use device_for_each_child_node_scoped() to simplify the code by removing
the need for explicit calls to fwnode_handle_put() in every error path.
This approach also accounts for any error path that could be added.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20240930-net-device_for_each_child_node_scoped-v2-2-35f09333c1d7@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>