LU-7078 llite: reset md->lmv to NULL

LU-7078 llite: reset md->lmv to NULL

ll_update_lsm_md() should reset md->lmv to NULL
right after it is assigned to lli_lsm_md, otherwise
it might be double freed if failure happens.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I4f069e3445a957860c2853c6f32104885edc33fa
Reviewed-on: http://review.whamcloud.com/16382
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>