please pick 552546366a30 to 5.4.y

Dear stable kernel maintainers, Please consider cherry-picking commit 552546366a30 ("hugetlbfs: hugetlb_fault_mutex_hash() cleanup") to linux-5.4.y. It first landed in v5.5-rc1 and fixes an instance of the warning -Wsizeof-array-div.

It cherry picks cleanly, I verified that I can build CONFIG_USERFAULTFD=y CONFIG_HUGETLBFS=y with it applied, and that none of the call sites of hugetlb_fault_mutex_hash have an issue with the signature change once applied to 5.4.y.