【OLK-5.10】hugetlb_vmemmap特性增强

回合hugetlb_vmemmap特性后续的几个增强：
1. Patch series "Free the 2nd vmemmap page associated with each HugeTLB page", v7.
    进一步优化内存节省，对于2M大页，只需要保留一个页的struct page。
2. Enable HUGETLB_PAGE_FREE_VMEMMAP for arm64
    支持在arm64上使能hugetlb_vmemmap特性
3. cleanup hugetlb_vmemmap
    重新整理了hugetlb_vmemmap的代码
4. add hugetlb_optimize_vmemmap sysctl
    支持通过sysctl控制开关hugetlb_vmemmap特性
5. 交换hugtlb_vmemmap和dynamic hugetlb的优先级
    当开启dynamic hugetlb特性时(默认关闭)，会关闭hugetlb vmemmap特性。

测试记录：
1. 测试了接口有效性
2. 测试了大页优化效果
3. 测试了selftest中关于大页的测试用例
```
-----------------------
disable hugetlb vmemmap
-----------------------
[PASS]
----------------------
enable hugetlb vmemmap
----------------------
[PASS]
---------------------------
test 2M optimization effect
---------------------------
enable free=26419320, disabled free=26275368
[PASS]
---------------------------
test 1G optimization effect
---------------------------
enable free=20092104, disabled free=19930088
[PASS]
---------------------
running hugepage-mmap
---------------------
Returned address is 0x7fa0f3400000
First hex is 0
First hex is 3020100
[PASS]
--------------------
running hugepage-shm
--------------------
shmid: 0x0
shmaddr: 0x7fd4bf400000
Starting the writes:
Starting the Check...Done.
[PASS]
-------------------
running map_hugetlb
-------------------
Default size hugepages
Mapping 256 Mbytes
Returned address is 0x7fca8e400000
First hex is 0
First hex is 3020100
[PASS]
------------------------
running hugepage-vmemmap
------------------------
Returned address is 0x7f9f04200000 whose pfn is 107a00
[PASS]
---------------------------
running userfaultfd_hugetlb
---------------------------
nr_pages: 64, nr_pages_per_cpu: 1
testing UFFDIO_ZEROPAGE: done.
testing signal delivery: done.
testing events (fork, remap, remove): userfaults: 64 missing (64), 0 wp (0)
[PASS]
```

GVP openEuler / kernel
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