NFS: Move call to nfs4_state_protect_write() to nfs4_write_setup()

This doesn't really need to be in the generic NFS client code, and I
think it makes more sense to keep the v4 code in one place.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>