nfs4: include open stateid into diagnostic printouts

like:

[dcache-lab000.desy.de] (dcache-lab002-A) admin > mover ls
4 : RUNNING : 0000DAF610008D6740EE98CAE1EB03DCFEAE h={NFSv4.1/pNFS,OS={[526654a200000001533ad0dd, seq: 55]},cl={131.169.185.68}} bytes=80740352 time/sec=0 LM=0

[dcache-lab000.desy.de] (nfsv41@nfs) admin > info
--- door (dCache implementation of NFSv4.1 MDS) ---
NFS ([3, 4.1]) door (MDS):
  IO queue:
  Known pools (DS):

    dcache-lab002-A : [DS: 00000002000000000000000000000000, InetAddress: [/131.169.191.142:33136]]

  Known movers (layouts):
    000084866518468F4B2D8F01516B27A4F64C : 1404@dcache-lab002-A, OS={[52664e9500000001f141762e, seq: 8]}

Acked-by: Paul Millar
Target: master, 2.6
Require-book: no
Require-notes: no