mm/hugetlb: reduce arch dependent code about hugetlb_prefault_arch_hook

Currently we have many duplicates in definitions of
hugetlb_prefault_arch_hook.  In all architectures this function is empty.

Signed-off-by: Zhang Zhen <zhenzhang.zhang@huawei.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc arch/arm/include/asm/hugetlb.h
Simple merge

diff --cc arch/arm64/include/asm/hugetlb.h
Simple merge

diff --cc arch/ia64/include/asm/hugetlb.h
Simple merge

diff --cc arch/metag/include/asm/hugetlb.h
Simple merge

diff --cc arch/mips/include/asm/hugetlb.h
Simple merge

diff --cc arch/powerpc/include/asm/hugetlb.h
Simple merge

diff --cc arch/s390/include/asm/hugetlb.h
Simple merge

diff --cc arch/sh/include/asm/hugetlb.h
Simple merge

diff --cc arch/sparc/include/asm/hugetlb.h
Simple merge

diff --cc arch/tile/include/asm/hugetlb.h
Simple merge

diff --cc arch/x86/include/asm/hugetlb.h
Simple merge

diff --cc fs/hugetlbfs/inode.c
Simple merge