mm/dynamic_hugetlb: isolate hugepage without dissolve

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6XOIE


CVE: NA

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The memory hotplug and memory failure will dissolve freed hugepages to
buddy system, this is not the expected behavior for dynamic hugetlb.
Skip the dissolve operation for hugepages belonging to dynamic hugetlb.
For memory hotplug, the hotplug operation is not allowed, if dhugetlb
pool existed. For memory failure, the hugepage will be discard directly.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>