LU-6961 ldiskfs: buffer head leak in mmp

Release bh_check in case of error.
patch added for following kernel
RHEL7.2 3.10.0-327.3.1.el7
SLES11SP3 3.0.101-0.47.55
SLES12 - since the code is fairly same across RHEL7 versions
adding the patch from RHEL7 to the SLES12 patch series.

Seagate-bug-id: MRP-2337
Signed-off-by: Jadhav Vikram <jadhav.vikram@seagate.com>
Change-Id: Ib3712abcc3e754077882f9302b6065e38e1f014c
Reviewed-on: http://review.whamcloud.com/17841
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Yang Sheng <yang.sheng@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>