mm/dynamic_pool: enable CONFIG_DYNAMIC_POOL on x86_64 and arm64 by default

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8S9BY


CVE: NA

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Enable CONFIG_DYNAMIC_POOL on x86_64 and arm64 by default.

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