LU-10391 lnet: discard lnet_nid2ni_*()

LU-10391 lnet: discard lnet_nid2ni_*()

These 'struct lnet_ni' lookup functions which take a nid4, are
discarded in favour of the versions which take a 'struct lnet_nid'.

Test-Parameters: trivial testlist=sanity-lnet
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: I4f4cb154e7778ac5b68cec3a40fc0d9a8a1db480
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/44634
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>