LU-9992 lnet: don't discover loopback interface

LU-9992 lnet: don't discover loopback interface

Whenever we send messages destined to the loopback interface
it should always go over the loopback interface. To achieve that
there is no real need to initiate discovery on the loopback.
This will result in a non-mr peer created for the loopback,
Which makes sense because if we are to send messages to
ourselves we do not want to use the different interfaces
rather just keep sending over the lolnd. In effect this
is a special case where we want to behave as a non-mr
node.

When sending a message destined for the loopback interface
there is no need to go through the selection process, it
is sufficient to shortcut all the MR logic and send directly
over the lolnd.

Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: I821a74e9dbe35481a0168389b857f07397cee126
Reviewed-on: https://review.whamcloud.com/29007
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Sonia Sharma <sonia.sharma@intel.com>
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>