NFSv4: Fix hangs when recovering open state after a server reboot

When we're using a cached open stateid or a delegation in order to avoid
sending a CLAIM_PREVIOUS open RPC call to the server, we don't have a
new open stateid to present to update_open_stateid().
Instead rely on nfs4_try_open_cached(), just as if we were doing a
normal open.

Fixes: d2bfda2e ("NFSv4: don't reprocess cached open CLAIM_PREVIOUS")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>