LU-6307 obdclass: distinguish MGC/MDT connection properly

LU-6307 obdclass: distinguish MGC/MDT connection properly

In the 5f8847bca12afb798de600299356ed2e3655a53e, we introduced the
version checking for the MDT-MDT connection. But there is a corner
that the MGC will set OBD_CONNECT_MNE_SWAB (that is defined as the
same as OBD_CONNECT_MDS_MDS) in the connection flags for Imperative
Recovery interoperability issues with MGS. So the server needs to
know whether the connection is really from another MDT or from the
MGC via checking OBD_CONNECT_FID (that is not set for the MGC-MGS
connection).

Test-Parameters: envdefinitions=ONLY=105 clientjob=lustre-b2_6 clientbuildno=19 testlist=recovery-small
Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: I9cee743d5474702b77adbb8c3dedd6c19faef15f
Reviewed-on: http://review.whamcloud.com/13927
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>