NFSv4: Fix a nfs4_state_manager() race

If the NFS4CLNT_RUN_MANAGER flag got set just before we cleared
NFS4CLNT_MANAGER_RUNNING, then we might have won the race against
nfs4_schedule_state_manager(), and are responsible for handling the
recovery situation.

Fixes: aeabb3c9

 ("NFSv4: Fix a NFSv4 state manager deadlock")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>