staging: lustre: lov: remove LSM from struct lustre_md

In struct lustre_md replace the struct lov_stripe_md *lsm member with
an opaque struct lu_buf layout which holds the layout metadata
returned by the server. Refactor the LOV object initialization and
layout change code to accommodate this. Simplify lov_unpackmd() and
supporting functions according to the reduced number of use cases.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5814
Reviewed-on: http://review.whamcloud.com/13722


Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>