mfd: qcom-spmi-pmic: Use for_each_child_of_node_scoped()

Avoids the need for manual cleanup of_node_put() in early exits
from the loop.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/r/20240826092734.2899562-3-ruanjinjie@huawei.com


Signed-off-by: Lee Jones <lee@kernel.org>