nfs/localio: remove 61 byte hole from needless ____cacheline_aligned

nfs/localio: remove 61 byte hole from needless ____cacheline_aligned

struct nfs_local_kiocb used ____cacheline_aligned on its iters[] array
and as the structure evolved it caused a 61 byte hole to form.  Fix
this by removing ____cacheline_aligned and reordering iters[] before
iter_is_dio_aligned[].

Fixes: 6a218b9c3183 ("nfs/localio: do not issue misaligned DIO out-of-order")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>