LU-13781 lnet: Local NI must be on same net as next-hop

When sending to a remote peer we need to restrict our selection of a
local NI to those on the same peer net as the next-hop.

The code currently selects a local NI on the peer net specified by the
lr_lnet field of the lnet_route returned by lnet_find_route_locked().
However, lnet_find_route_locked() may select a next-hop peer NI on any
local peer net - not just lr_lnet.

A redundant assignment to sd->sd_msg->msg_src_nid_param is also
removed. That variable is always set appropriately in
lnet_select_pathway().

Test-Parameters: trivial
HPE-bug-id: LUS-9095
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: If1bec26d6646b9e66b99656d7db2dc538d631a34
Reviewed-on: https://review.whamcloud.com/39352
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>