LU-19075 o2iblnd: reduce memory usage

LU-19075 o2iblnd: reduce memory usage

ib_recv_wr / ib_sge are not needed after ib_post_recv finished.
lets remove it.

Test-Parameters: trivial
Signed-off-by: Alexey Lyashkov <alexey.lyashkov@hpe.com>
Change-Id: Id866c1bbaeafa41103ef7caa8a1254c53c9e3c3d
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/59488
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Andrew Perepechko <andrew.perepechko@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>