LU-4136 obdclass: use obd_get_info to report network status

Use obd_get_info() to report MDT-OST connection status instead of
health_check(), so that /proc/fs/lustre/health_check does not
check MDT's connection status.

Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Change-Id: I8b4afcfdce3712fff893475b9c5cd44654f3762e
Reviewed-on: http://review.whamcloud.com/8408
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>