LU-3162 lov: Get the correct address of lmm_objects

LU-3162 lov: Get the correct address of lmm_objects

The introduction of lmm_layout_gen makes the assumption that
lmm_objects is present after lmm_stripe_count incorrect.
Fixed this to get the correct address of lmm_objects when lmmk is cast
to lov_mds_md_v1.

Signed-off-by: Swapnil Pimpale <spimpale@ddn.com>
Change-Id: I6eba151a54862fde60f4382df92864a52bb12530
Reviewed-on: http://review.whamcloud.com/7258
Tested-by: Hudson
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>