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().

Lustre-change: https://review.whamcloud.com/44730
Lustre-commit: 98da4ace43a6c4c59e7981bf0fb649005237d12f

Test-Parameters: trivial testlist=sanity-lnet
HPE-bug-id: LUS-10301
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: Ie47558d5bce97a0dca30ff7d072dcd39eb903324
Reviewed-on: https://review.whamcloud.com/48441
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Alexandre Ioffe <aioffe@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>