LU-5418 echo: replace lov_stripe_md with lov_oinfo

LU-5418 echo: replace lov_stripe_md with lov_oinfo

In echo_client replace uses of struct lov_stripe_md with struct
lov_oinfo (since the instances of the former really only contained a
single instance of the latter). Remove the then unneccessary functions
echo_alloc_memmd(), echo_free_memmd(), osc_unpackmd(), and
obd_alloc_memmd(). Remove the struct lov_stripe_md * parameter from
obd_create(). Flatten osc_create() and osc_real_create() into a single
function.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I5fe276bcc56e1fa8138a4d3f20b9d5297cf74f3f
Reviewed-on: http://review.whamcloud.com/12447
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>