rust: sync: atomic: Fix fmt warning

Commit 14e9a18b07ec ("rust: sync: atomic: Make Atomic*Ops pub(crate)")
introduced an import ordering that rustfmt disagrees with. Hence fix it.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/lkml/202512110753.8B3YlvtX-lkp@intel.com/
Fixes: 14e9a18b07ec ("rust: sync: atomic: Make Atomic*Ops pub(crate)")
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>