LU-14941 lnet: Fix source specified to routed destination

LU-14941 lnet: Fix source specified to routed destination

If a source NI is specified for a send then we should not modify the
destination NID that was passed to lnet_send().

HPE-bug-id: LUS-10301
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: Ie47558d5bce97a0dca30ff7d072dcd39eb903324
Reviewed-on: https://review.whamcloud.com/44730
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>