NFS: Don't immediately return directory delegations when disabled

NFS: Don't immediately return directory delegations when disabled

The function nfs_inode_evict_delegation() immediately and synchronously
returns a delegation when called. This means we can't call it from
nfs4_have_delegation(), since that function could be called under a
lock. Instead we should mark the delegation for return and let the state
manager handle it for us.

Fixes: b6d2a520f463 ("NFS: Add a module option to disable directory delegations")
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>