mm: hugetlb_vmemmap: move mmap lock to vmemmap_remap_range()

All the users of vmemmap_remap_range() will hold the mmap lock and release
it once it returns, it is naturally to move the lock to
vmemmap_remap_range() to simplify the code and the users.

Link: https://lkml.kernel.org/r/20231205030853.3921-1-songmuchun@bytedance.com


Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>