NFS/pnfs: handle bad delegation stateids in nfs4_layoutget_handle_exception

We must call nfs4_handle_exception() on BAD_STATEID errors. The only
exception is if the stateid argument turns out to be a layout stateid
that is declared invalid.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>