ACPI: memhotplug: export the state of each hotplug device

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8OWS6


CVE: NA

---------------------------------------------------------

Export the state of a hotplug memory device, and driviers
can use this information to manipulate the hotplug memory
device.

Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>