regulator: bd718x7: Use scoped device node handling to simplify error paths

Obtain the device node reference with scoped/cleanup.h and use scoped
for_each_child_of_node_scoped() to reduce error handling and make the
code a bit simpler.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20240814-cleanup-h-of-node-put-regulator-v1-1-87151088b883@linaro.org


Signed-off-by: Mark Brown <broonie@kernel.org>