EX-4218 lipe: Fix assertion in lipe_ssh_session_create

EX-4218 lipe: Fix assertion in lipe_ssh_session_create

Return SSH_ERROR code in all faulty cases
Add reporting libssh return error code

Signed-off-by: Alexandre Ioffe <aioffe@ddn.com>
Test-Parameters: trivial testlist=hot-pools
Change-Id: I84d5c3d1fe0e6d1c7818ec181a7b9ea07413eb8a
Reviewed-on: https://review.whamcloud.com/45638
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/46127