LU-9119 lnet: selftest MR fix

LU-9119 lnet: selftest MR fix

selftest always responded to the primary nid of the peer rather than
the source of the message, which it should be.

Test-Parameters: trivial
Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Signed-off-by: Olaf Weber <olaf@sgi.com>
Change-Id: I14a4b6ffc5882cb23298429d8a4bd0bcb0a8a5be
Reviewed-on: https://review.whamcloud.com/26723
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>