LU-6906 mgc: IR log failure should not stop mount

LU-6906 mgc: IR log failure should not stop mount

If clients or other targets can not get IR config lock
or lock, the mount should continue, instead of failing.
Because timeout mechanism will handle the recovery anyway.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ie717cb363180907b510593ee4a6caaec6f07a5f3
Reviewed-on: http://review.whamcloud.com/15728
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>