kernel: arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud

In the Linux kernel, the following vulnerability has been resolved: arm64/mm: fix incorrect filemapcount for non-leaf pmd/pud The page table check trigger BUGON unexpectedly when collapse hugepage: ------------ cut here ------------ kernel BUG at mm/pagetablecheck.c:82! Internal error: Oops - BUG...