LU-10391 lnet: change lpni_nid in lnet_peer_ni to lnet_nid

LU-10391 lnet: change lpni_nid in lnet_peer_ni to lnet_nid

lpni_nid in 'struct lnet_peer_ni' is converted to 'struct lnet_nid'
and various supporting functions updated.

Test-Parameters: trivial
Test-Parameters: serverversion=2.12 serverdistro=el7.9 testlist=runtests
Test-Parameters: clientversion=2.12 testlist=runtests
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I7a99f758b600a0dd0668edd368663ff65f603486
Reviewed-on: https://review.whamcloud.com/42101
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>