LU-10391 lnet: Change LNetDist to work with struct lnet_nid

LU-10391 lnet: Change LNetDist to work with struct lnet_nid

LNetDist now takes and returns 'struct lnet_nid'
lustre_uuid_to_peer() is also updated.

The 'dst' and 'src' parameters to LNetDist are now both pointers, and
that can point to the same 'struct lnet_nid'.  Code needs to be
careful not to set *src until after the last use of *dst.

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: I267f3333e3164778a7df39d6b90f0a9a913fcdcf
Reviewed-on: https://review.whamcloud.com/43618
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>