LU-966 mdd: revert commit and use original patch

LU-966 mdd: revert commit and use original patch

Use original patch which replaces LASSERT with CERROR in MDD,
because checking object exists in MDT ruins VBR recovery.
It happens too early but VBR should check that too before reply
to the client.

Signed-off-by: Mikhail Pershin <tappro@whamcloud.com>
Change-Id: If31586c9d1cc86c4c8059a7227c231acdc82a0f1
Reviewed-on: http://review.whamcloud.com/2148
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Niu Yawei <niu@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Yu Jian <yujian@whamcloud.com>
Tested-by: Yu Jian <yujian@whamcloud.com>