until it hits top of the list.
 Once the RPC call has completed, it can then bump the sequence id counter,
 and remove itself from the rpc_sequence list, and then wake up the next
 sleeper.

 Note that the state_owner sequence ids and lock_owner sequence ids are
 all indexed to the same rpc_sequence list, so OPEN, LOCK,... requests
 are all ordered w.r.t. each other.

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