mm: revert "mm: shmem: fix data-race in shmem_getattr()"

mm: revert "mm: shmem: fix data-race in shmem_getattr()"

Revert d949d1d14fa2 ("mm: shmem: fix data-race in shmem_getattr()") as
suggested by Chuck [1].  It is causing deadlocks when accessing tmpfs over
NFS.

As Hugh commented, "added just to silence a syzbot sanitizer splat: added
where there has never been any practical problem".

Link: https://lkml.kernel.org/r/[email protected]
Fixes: d949d1d14fa2 ("mm: shmem: fix data-race in shmem_getattr()")
Acked-by: Hugh Dickins <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Jeongjun Park <[email protected]>
Cc: Yu Zhao <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>