hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I650K6

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1. Extract a function that initialize all the members for a newly
   allocated sp_group. Just to decrease the function size.
2. Move the idr_alloc to the end of the function, since we should not
   add an uninitialized sp_group to the global idr.
3. Rename the file for hugetlb map.
Signed-off-by: NWang Wensheng <wangwensheng4@huawei.com>