ACPI: bus: Export acpi_dev_for_each_child() to modules

mainline inclusion
from mainline-v6.0-rc1
commit f8128c39
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I67QNJ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=f8128c390e58928b16f197416d417cfa4c65f610



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Some pieces of modular code can benefit from using
acpi_dev_for_each_child(), so export it to modules.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>