LU-16709 lnet: fix locking multiple NIDs of the MR peer

LU-16709 lnet: fix locking multiple NIDs of the MR peer

If Lustre identifies the same peer with multiple NIDs,
as a result of peer discovery it is possible that
the discovered peer is found to contain a NID which is locked
as primary by a different existing peer record.
In this case it is safe to merge the peer records,
but the NID which got locked the earliest should be
kept as primary.

This allows for the first of the two locked NIDs
to stay primary as intended for the purpose of communicating
with Lustre even if peer discovery succeeded
using a different NID of MR peer.

Fixes: aacb16191a ("LU-14668 lnet: Lock primary NID logic")
Signed-off-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Change-Id: Iec9f8b70053fe24cddee552358500dfad0234b7f