vmalloc: Add config for Extend for hugepages mapping

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6HRGK



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Use CONFIG_EXTEND_HUGEPAGE_MAPPING to isolate code
introduced in a3425d41.

Besides, use tab instead of space to match the format
of Kconfig

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