NFSv4: Fix memory and state leak in _nfs4_open_and_get_state

If we exit because the file access check failed, we currently
leak the struct nfs4_state. We need to attach it to the
open context before returning.

Fixes: 3efb9722

 ("NFSv4: Refactor _nfs4_open_and_get_state..")
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>