LU-14549 llite: refresh layout after mirror merge/split

LU-14549 llite: refresh layout after mirror merge/split

mirror merge/split updates file's LOVEA and revokes client's layout
lock, but the client issuing the layout change needs to refresh its
layout (lov->lsm) as well.

Lustre-change: https://review.whamcloud.com/43716
Lustre-commit: bd7a20f8be4644ebce6a7225560ae933204f543d

Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: I7671efe2fe5354ba0e1503b146045165608e042c
Reviewed-by: Wang Shilong <wshilong@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/44252
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>