NFSv4.1: CB_RECALL_SLOT must schedule a sequence op after updating targets

RFC5661 requires us to make sure that the server knows we've updated
our slot table size by sending at least one SEQUENCE op containing the
new 'highest_slotid' value.
We can do so using the 'CHECK_LEASE' functionality of the state
manager.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>