NFSv4: Ensure that we recover from the OPEN + OPEN_CONFIRM BAD_STATEID race

 If the server is in the unconfirmed OPEN state for a given open owner
 and receives a second OPEN for the same open owner, it will cancel the
 state of the first request and set up an OPEN_CONFIRM for the second.

 This can cause a race that is discussed in rfc3530 on page 181.

 The following patch allows the client to recover by retrying the
 original open request.

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